Nebula 2.23 problems

Hi Guys

I have both Nebula 2.23 (the hack version) and Nebula 2.24

In nebula 2.24 the rom cthd2003 (Crouching Tiger Hidden Dragon 2003) works perfectly, however if I copy the data file to the Nebula 2.23 emulator and try to load the rom in Nebula 2.23 even though the rom is recognised and loads perfectly I just get a black screen??

Any ideas on the problem?? the rom, bios and dat files are all correct?

Also the kof2003 rom has the same problem in Nebula 2.23 (i.e loads perfectly but I just get a black screen) all other roms e.g mslug5nd, samsho5 etc work perfectly

Thanks and any help greatly appreciated