Panasonic DMP-BD87 DLNA file compatibility - won't play mkv files

Just picked up the Panasonic DMP-BD87. Actually sort of just stumbled into the DLNA part of a blu-ray so really did not pay much attention to this when I got it. Once it was hooked up and I was playing around with it, my very slow brain finally picked up how valuable this could be. Of course then i discovered that it will pretty much only stream mkv files. So, picked out a mkv file and it comes up with a "can't play" error. Looked around in the manual and it briefly mentions it can't play all mkv files (seriously, what is the point on this, it basically streams nothing) but the manual does not give any specs on what it can play.

Would be nice if I could figure it out. It does the flacs great but I do occasionally do a movie or 2. Anyone have any info on what the requirements are ?

Thanks