I''ve been working with the grouping control and am programmatically setting up basically all of it since I''ve been experiencing problems with the designer, persistence and Visual Studio stability. But onto my comment, on the Grid Expanding I don''t believe there is appropriate error handling for checking that the relation exists. I came to this conclusion when I was getting a null reference exception in Grouping.dll when trying to expand the grid to show children records. The mappingname I specified for the gridrelationdescripter was not syncronized with the relation name in the dataset and was causing the problem. I got lucky and tried changing it which fixed the problem but the runtime error did nothing to help me understand what my problem was.