I don't have the devex controls loaded on this machine, so I can't test it on that particular grid, but you should be handling the validation at the BO level rather than in an event within the grid. I've attatched a version of the Business Binding Source sample that has been updated to work with VS 2008. Run the sample, delete the first or last name of any row, then try to save. You'll see that the BO will handle the validation and show the error provider in the appropriate position.