Field names not populating in rad filter

[Brian]

I have followed the example on the site for implementing the RadFilter with a grid.  The control displays, but I get the following error:

 Line: 6
Error: Sys.WebForms.PageRequestManagerServerErrorException: Parameter cannot be null or empty.
Parameter name: fieldName 

This occurs whenever I click the add expression button.

Any help would be appreciated.

Thanks...Brian

[Martin]

Hello Brian,

Could you please provide the url of the demo you have referenced? In case you have modified the code in a local sample based on the demo, please consider opening a formal support ticket and send it to me for an inspection. Once I have a sample code to debug, I would be able to provide more to the point resolution.

All the best,
Martin
the Telerik team