XBM demo disc problem

[LiOnHeArTbLaDeX]

Just recieved my XBM magazine and demo disc.From the looks of the previews of UC2TLC,i wanna play it!of course it's on the disc but when i try to play the Unreal Championship 2:The Liandri Conflict it gives me error #21.I'm trying to play it on a modded xbox...softmodded.All the other demos work good except UC2TLC.Does anyone else have this problem?Don't delete this please!!!until someone has replied to the question and i post a reply, after my reply go ahead and delete it.Thanks