--- a/controls/PouInstanceVariablesPanel.py	Sun Jun 03 23:47:13 2012 +0200
+++ b/controls/PouInstanceVariablesPanel.py	Sun Jun 03 23:47:56 2012 +0200
@@ -132,7 +132,7 @@
         self.InstanceChoice.Clear()
         self.InstanceChoice.SetValue("")
         
-        if self.PouTagName is not None:
+        if self.Controller is not None and self.PouTagName is not None:
             self.PouInfos = self.Controller.GetPouVariables(self.PouTagName, self.Debug)
         else:
             self.PouInfos = None