diff --git a/include/wochenplan.class.php b/include/wochenplan.class.php
index a5f0d330b..7ce210ef6 100644
--- a/include/wochenplan.class.php
+++ b/include/wochenplan.class.php
@@ -1474,7 +1474,7 @@ class wochenplan extends basis_db
 		{
 			for ($s=$min_stunde;$s<=$max_stunde;$s++)
 			{
-				$raster[$t][$s]->ort=array();
+				@$raster[$t][$s]->ort=array();
 				$raster[$t][$s]->kollision=false;
 			}
 		}