Unable to play mkv/Real (1 Viewer)

[Mouch.net]

Some of my MKV are coded with Real codec.
I can play them withour problem in GraphStudio but when I try to start them from TV-Series I get following codec error:

Video : V_Real/RV40
Audio: Cooker

Screenshots:

Any Idea ???

 

[kkendall]

Same problem here, but with rmvb files:
Video : RV40
Audio: Cooker

rmvb files do play in Windows Media Player...but not in Mediaportal. That sounds to me like a Mediaportal bug.
Anybody with some info or extra explanation on this issue?