diff --git a/api/app/Http/Controllers/ProgramController.php b/api/app/Http/Controllers/ProgramController.php
index 0f47043..6ab7f21 100644
--- a/api/app/Http/Controllers/ProgramController.php
+++ b/api/app/Http/Controllers/ProgramController.php
@@ -54,7 +54,7 @@ QUERY;
       $endDay = $end->format('N');
       $schedule = [];
 
-if($DEBUG) print "Creating schedule between {$start->format('Y-m-d H:i')} and {$end->format('Y-m-d H:i')}<br/>\n";
+      if($DEBUG) print "Creating schedule between {$start->format('Y-m-d H:i')} and {$end->format('Y-m-d H:i')}<br/>\n";
  
       $START = 1; $END = -1;
       $WEEK = new \DateInterval('P7D'); $DAY = new \DateInterval('P1D');
@@ -68,38 +68,46 @@ if($DEBUG) print "Creating schedule between {$start->format('Y-m-d H:i')} and {$
         if($item->enddate) { $item->enddate = (new \DateTimeImmutable($item->enddate))->add($DAY); }
 
         // Find the start time and end time of the last occurrence on or before the start time
-        $itemStart = new \DateTime("last " . $WEEKDAYS[$item->startday] . " " . $start->format('Y-m-d') . " " . $item->starttime);
-        $itemEnd = new \DateTime("last " . $WEEKDAYS[$item->endday] . " " . $start->format('Y-m-d') . " " . $item->endtime);
+        $itemStart = new \DateTimeImmutable("last " . $WEEKDAYS[$item->startday] . " " . $start->format('Y-m-d') . " " . $item->starttime);
+        $itemEnd = new \DateTimeImmutable("last " . $WEEKDAYS[$item->endday] . " " . $start->format('Y-m-d') . " " . $item->endtime);
 
         if($itemEnd <= $itemStart) {
-          $itemEnd->add($WEEK);
+          $itemEnd = $itemEnd->add($WEEK);
         }
 
         // If the first occurrence is completely before the period of interest, look at the next week
         while($itemEnd < $start) { 
-          $itemStart->add($WEEK);
-          $itemEnd->add($WEEK);
+          $itemStart = $itemStart->add($WEEK);
+          $itemEnd = $itemEnd->add($WEEK);
         }
 
-        if($DEBUG) { 
-          print "Adding {$item->name} (#$item->scheduleid) at {$itemStart->format('Y-m-d H:i')} to {$itemEnd->format('Y-m-d H:i')}.<br/>\n";
-          if($item->startdate) print " (Item start is {$item->startdate->format('Y-m-d H:i')})<br/>\n";
-        }
-
-        if((!$item->startdate || $item->startdate <= $itemEnd) && (!$item->enddate || $item->enddate >= $itemStart)) {
-          // Create a list in which all start and end times are separate entries
-          $scheduleChanges->insert( [$START, $itemStart, $item], [-$itemStart->getTimestamp(), -$START] );
-          $scheduleChanges->insert( [$END, $itemEnd, $item], [-$itemEnd->getTimestamp(), -$END] );
-        } else if($DEBUG) {
-          print "Skipping {$item->name} (#$item->scheduleid) at {$itemStart->format('Y-m-d H:i')} because it is out of range.<br/>\n";
-        }
-
-        // Also keep track of all priorities seen
-        $active[$item->priority] = null;
+        while($itemEnd <= $end) {
+            if($DEBUG) { 
+              print "Considering {$item->name} {$item->suffix} (#$item->scheduleid) at {$itemStart->format('Y-m-d H:i')} to {$itemEnd->format('Y-m-d H:i')}.<br/>\n";
+              if($item->startdate) print "-- (Item start is {$item->startdate->format('Y-m-d H:i')}, end is ". ($item->enddate ? $item->enddate->format('Y-m-d H:i') : "never") . ")<br/>\n";
+            }
+    
+            if($item->startdate && $itemStart <= $item->startdate) {
+              if($DEBUG) print "-- Skipping {$item->name} {$item->suffix} (#$item->scheduleid) at {$itemStart->format('Y-m-d H:i')} because it is before the schedule instance start.<br/>\n";
+            } else if($item->enddate && $itemStart >= $item->enddate) {
+              if($DEBUG) print "-- Skipping {$item->name} {$item->suffix} (#$item->scheduleid) at {$itemStart->format('Y-m-d H:i')} because it is after the schedule instance end.<br/>\n";
+            } else {
+              // if($DEBUG) print "-- Adding {$item->name} {$item->suffix} (#$item->scheduleid) at {$itemStart->format('Y-m-d H:i')} <br/>\n";
+              // Create a list in which all start and end times are separate entries
+              $scheduleChanges->insert( [$START, $itemStart, $item], [-$itemStart->getTimestamp(), -$START] );
+              $scheduleChanges->insert( [$END, $itemEnd, $item], [-$itemEnd->getTimestamp(), -$END] );
+            }
+    
+            // Also keep track of all priorities seen
+            $active[$item->priority] = null;
+ 
+            $itemStart = $itemStart->add($WEEK);
+            $itemEnd = $itemEnd->add($WEEK);
+          }
       }
 
       if($DEBUG) { 
-        print "<h2>Schedule changes - initial state</h2><ul>";
+        print "<h2>Schedule changes</h2><ul>";
         foreach(clone $scheduleChanges as $c) { 
           print "<li>#{$c[2]->scheduleid}: {$c[1]->format('d-m-Y H:i')}: " . ($c[0] == $START ? 'Start' : 'Einde') . " {$c[2]->name} {$c[2]->suffix}</li>";
         }
@@ -109,44 +117,36 @@ if($DEBUG) print "Creating schedule between {$start->format('Y-m-d H:i')} and {$
       // Go through all programs and keep going until we have one that starts after the end date.
       $activeProgram = null;
       $activeProgramStart = null;
-      while(true) {
+      while(!$scheduleChanges->isEmpty()) {
         $item = $scheduleChanges->extract();
-
+        
         // If we passed the end time, we are (almost) done
         if($item[1] > $end) {
           if($DEBUG) { print "Reached end at {$item[1]->format('d-m-Y H:i')} ({$item[2]->name}).<br/>"; }
           break;
         }
 
-        // Only use this item if it is valid
-        // MS 2018-01-12: Don't know why I originally had this, the list should only contain valid items.
-        //                This crashed the site once because it skipped a program that should have been in the list but generated 'program not active at priorty' message later on.
-        // if(($item[2]->startdate == null || $item[2]->startdate <= $activeProgramStart) && ($item[2]->enddate == null || $item[2]->enddate > $activeProgramStart))
-        {
-          if($DEBUG) print "<b>{$item[1]->format('d-m-Y H:i')}: {$item[2]->name} {$item[2]->suffix} " . ($item[0] == $START ? "begint" : "eindigt") . "</b><br/>";
+        $priority = $item[2]->priority;
+        if($item[0] == $START) { 
+          if($active[$priority] != null) { 
+            print( "<b>Error:</b>" . $item[2]->name . ' starts at ' . $item[1]->format('d-m-Y H:i') . ' but ' . $active[$priority]->name . ' is still active then.' );
+            print "<pre>"; var_dump($active); print "</pre>";
+          }
     
-          $priority = $item[2]->priority;
-          if($item[0] == $START) { 
-            if($active[$priority] != null) { 
-              print( "<b>Error:</b>" . $item[2]->name . ' starts at ' . $item[1]->format('d-m-Y H:i') . ' but ' . $active[$priority]->name . ' is still active then.' );
-              print "<pre>"; var_dump($active); print "</pre>";
-            }
-    
-            // When a program starts, it becomes the active program in its layer
-            $active[$priority] = $item[2];
-  
-            // In addition, if it has higher priority than the currently active program, it replaces that. 
-            if($activeProgram == null || $priority < $activeProgram->priority) {
-                if(($activeProgram != null) && ($item[1] > $start)) {
-                  if($DEBUG) print "{$activeProgramStart->format('d-m-Y H:i')} -- {$item[1]->format('d-m-Y H:i')}: {$activeProgram->name} (reason: {$item[2]->name} starts).<br/>";
-                  $this->addToSchedule($schedule, $activeProgramStart, $item[1], $activeProgram);
-                }
-  
-              $activeProgramStart = ($item[1] < $start) ? $start : clone $item[1];
-              $activeProgram = $item[2];
-            }
-  
-          } else if($item[0] == $END) {
+          // When a program starts, it becomes the active program in its layer
+          $active[$priority] = $item[2];
+
+          // In addition, if it has higher priority than the currently active program, it replaces that. 
+          if($activeProgram == null || $priority < $activeProgram->priority) {
+              if(($activeProgram != null) && ($item[1] > $start)) {
+                if($DEBUG) print "{$activeProgramStart->format('d-m-Y H:i')} -- {$item[1]->format('d-m-Y H:i')}: {$activeProgram->name} (reason: {$item[2]->name} starts).<br/>";
+                $this->addToSchedule($schedule, $activeProgramStart, $item[1], $activeProgram);
+              }
+
+            $activeProgramStart = ($item[1] < $start) ? $start : clone $item[1];
+            $activeProgram = $item[2];
+          }
+         } else if($item[0] == $END) {
             if($active[$priority] == null) {
               print( "<b>Error:</b>" . $item[2]->name . ' ends at ' . $item[1]->format('d-m-Y H:i') . ' but no program is active at that priority and timestamp.');
               print "<pre>"; var_dump($active); print "</pre>";
@@ -157,7 +157,7 @@ if($DEBUG) print "Creating schedule between {$start->format('Y-m-d H:i')} and {$
   
             // In addition, when the ending program was the active program, we need to schedule it and find the new currently active program
             if($activeProgram == $item[2]) {
-              if($DEBUG) print "{$activeProgramStart->format('d-m-Y H:i')} -- {$item[1]->format('d-m-Y H:i')}: {$activeProgram->name} (reason: {$item[2]->name} ends).<br/>";
+              if($DEBUG) print "{$activeProgramStart->format('d-m-Y H:i')} -- {$item[1]->format('d-m-Y H:i')}: {$activeProgram->name} {$activeProgram->suffix} (reason: {$item[2]->name} ends).<br/>";
               $this->addToSchedule($schedule, $activeProgramStart, $item[1], $activeProgram);
   
               $activeProgram = null;
@@ -170,26 +170,14 @@ if($DEBUG) print "Creating schedule between {$start->format('Y-m-d H:i')} and {$
               if($activeProgram != null) {
                 $activeProgramStart = clone $item[1];
               }
-  
-              if($DEBUG) print "  New active program is " . ($activeProgram ? $activeProgram->name : "---") . "<br/>";
             }
           } else {
             return response()->abort(500, "Invalid item type: expected START ($START) or END ($END), but got {$item[0]}.");
           }
-        //} else if($DEBUG) {
-        //  print "<i>Skipped {$item[2]->name} {$item[2]->suffix} on {$item[1]->format('d-m-Y H:i')} <br/>"
-        //      . " &nbsp;&nbsp; because startdate is " . ($item[2]->startdate == null ? "[null]" : $item[2]->startdate->format('d-m-Y H:i')) . " <br/>"
-        //      . " &nbsp;&nbsp; and end date is " . ($item[2]->enddate == null ? "[null]" : $item[2]->enddate->format('d-m-Y H:i')) . " <br/>" 
-        //      . " &nbsp;&nbsp; Active program " . ($activeProgram ? $activeProgram->name : '[null]') . " starts at " . $activeProgramStart->format('c') . "</i><br/>"; 
-        }
-
-        // The item will recur in a week
-        $item[1]->add($WEEK);
-        $scheduleChanges->insert($item, [-$item[1]->getTimestamp(), -$item[0]]);
       }
   
       if(($activeProgram != null) && ($activeProgramStart != $end)) {
-        if($DEBUG) print "{$activeProgramStart->format('d-m-Y H:i')} -- {$end->format('d-m-Y H:i')}: {$activeProgram->name} (reason: schedule finished).<br/>";
+        if($DEBUG) print "{$activeProgramStart->format('d-m-Y H:i')} -- {$end->format('d-m-Y H:i')}: {$activeProgram->name} {$activeProgram->suffix} (reason: schedule finished).<br/>";
         $this->addToSchedule($schedule, $activeProgramStart, $end, $activeProgram);
       }
   
@@ -200,7 +188,8 @@ if($DEBUG) print "Creating schedule between {$start->format('Y-m-d H:i')} and {$
     {
       $start = new \DateTimeImmutable(urldecode($from));
       $end = new \DateTimeImmutable(urldecode($to));
-      print '<pre>'  . json_encode($this->createSchedule($start, $end, true)) . '</pre>';
+      $this->createSchedule($start, $end, true);
+      return "";
     }