--- a/graphics/GraphicCommons.py	Wed Dec 09 10:19:35 2009 +0100
+++ b/graphics/GraphicCommons.py	Wed Dec 09 16:50:19 2009 +0100
@@ -245,7 +245,7 @@
         if self.RegisterTick and self.Debug:
             if producer is not None:
                 producer.SubscribeDebugIECVariable("__tick__", self)
-            elif self.DataProducer is not None:
+            if self.DataProducer is not None:
                 self.DataProducer.UnsubscribeDebugIECVariable("__tick__", self)        
         self.DataProducer = producer