[rudedog]

1st make sure you unzip the file first. should be a pk3 file.
Place this file in your main dir. ( may sound simple but many forget to do this - no offence if you have done this already )

If you have done that, try this

make sure you have wall decals checked
toggle texture compression. depending on how the mod was made you may have to set it to the opposite of what your currently using

Both can be found main menu -> video