Bugfix

db/upgrade.php

@@ -359,8 +359,9 @@ function xmldb_local_treestudyplan_upgrade($oldversion) {
                     // If no end time is given, assume a year duration for period calculations
                     $ydelta = (365*24*60*60)/$pcount;
                 }
-
+                else{
                     $ydelta = $yend - $ystart;
+                }
                 $ptime = $ydelta / $pcount;
 
                 for($i=0; $i < $pcount; $i++){