I am using the Excel-like filtering in my Winforms application and I have a few GridViewComboBoxColumns that have their datasources set from stored procedures programatically instead of from the database table that I am using for the datasource for the rest of the columns. Because of this, the filters are not automatically filling in the options for these columns like they do for the columns that use the main datasource. I have used the technique described here: https://www.telerik.com/forums/custom-gridview-filter-popup to add custom options to the filters where needed, but once selected and OK is clicked, nothing happens. When I add a break point in the FilterChanging event, I see that the column has been selected as a filter source based on the Property Name, but there is no value and no expression in the filter. Is there something I have to do to format the values added to the DistinctListValues so that they pass a value and expression?