sound MOD problems

Hello fellow cod players. I am a sound effects artist for dod and a couple of other mods. I was just having one problem.

I open pk3 files and I replaced some sounds in the pk.3. I save it and then I start call of duty multiplayer. When I go into other peoples server, it connects me and right when I get to the main choose (axis or allies) or spectate… the server kicks me and says that an un-pure client
bad pk.3 files referenced.

But they cant be bad because they are of same quality.