MKV not showing up in just extender library

[cncb]

I have registered the MKV file type for WMC and can play it fine on WMC on my PC. However, even though MKV shows up in the PC library it is missing/not recognized on my extender (XBox 360) library - the same folder just shows an empty folder in the Videos library. Is there some step I'm missing to get these to show up on the extender library? Thanks.

[cncb]

I don't know why, but I had to manually add a registry item in the "classes" key for the extender while it was connected so it would recognize mkv files.