I looked through the DM8 manual only to find it the same (regarding cymbals) as the DM10. There is no specific choke setting beyond sending or not sending the MIDI information. Check to make sure you have the correct cymbal as your choke enabled crash and also check to make sure you have the correct cable (I think this is TRS/Stereo).
There have been a few folks on here that had the hihat and crash mixed up.