Hello,

E.g. the ResourceExpressionEditor displays a warning about a wrong expression by turning the webcontrol into a greybox with a message written onto it. I want my own custom expression editor behave the same way, but no matter what I do it does not work: Actually both, returning null and throwing an exception in EvaluateExpression, does not work. As a result only the control's ID is displayed instead of the evaluated expression. I also compared my ExpressionEditor with the ResourceExpressionEditor by using .Net Reflector, but I have not been able to figure out how the ResourceExpressionEditor generates this message, as both ExpressionEditors are working similiar.

Thanks for your Help

Kabelsalat

Sorry for bothering you, but actually it worked all the time. I was simply testing the wrong way: I didn't type in a wrong expression, I only changed the code of the EvaluateValue function of my ExpressionEditor class... know I've typed in a wrong expression - and it realy worked due to an exception being thrown by the ParseExpression-Function of the ExpressionBuilder!