L4D func_breakable_surf problem

[monkeyclass]

Was told to post here

Hi, I have a little problem when creating glass in L4D using the new SDK. I have made a func_breakable_surf and put nodraw on all sides except one, where I have put a glass texture that works as Func_breakable_surf in No_mercy. My problem is that when I load the map up and plays it, it looks fine, but when I shoot the glass it gives the purple/black texture. Help please