I don't think I got your point. In my case, my grid bound to a class has field column 1/0, 1 means Yes, 0 means No. So when I display the data, I switched 1/0 to Yes/No. So when I try to do the filter, I type "Yes", I suppose to get Yes only back, but instead I get everything back, which means the filter doesn't work.
I don't see there are connection between your example and mine case. As long as the grid already displayed Yes/No, when the user type Yes, it should automatically return Yes only, is it?