If you've specified an the groupname or skin incorrectly, then it certainly won't do the desired result.
Why? Does the shader name has to be the group name or the MD3 name?
You will need the full absolute path to the texture there. MD3s never load textures with relative paths.
An absolute path inside the shader or inside the MD3? This doesn't make sense, after all, the texture is loaded on the shader, not on the MD3!