B1900C prop textures: why doesn't work like the D version?

Hi guys!I've seen that the prop fix found here on AVSIM works great with the B1900D version but it doesn't work in the C version!! Anybody know the problem, or how to fix it??? I've tried to convert the prop texture file with the dxtbmp program, but nothing.Why it works on D version and not in the C???Thanks Paolo