--- a/Dialogs.py	Thu Sep 20 17:38:27 2007 +0200
+++ b/Dialogs.py	Tue Oct 02 18:00:13 2007 +0200
@@ -526,7 +526,7 @@
             values["name"] = expression
         else:
             values["name"] = self.VariableName.GetStringSelection()
-        values["value_type"] = ""
+        values["value_type"] = None
         for var_name, var_type, value_type in self.VarList:
             if var_name == values["name"]:
                 values["value_type"] = value_type