The great background of super bomber man 4, can be used in a title screen, space, abstract or galaxy levels, uses the palette no 7. To make the BG work properly, set the background to "none"
Palmask is wrong. The x means that color isn't included, you included about 95% of the entire palette here. Please make sure ONLY the colors used are in the palmask. Every color not used should have an X. This current palette will overwrite everyone's existing palettes which defeats the purpose of using a palmask.
Also, not a rejection reason, but see where all this pink background color is? It was originally the same shade of blue as the background of those clocks and stars. Since that's the case, that color can be changed to the transparent color index (which is color 0) because they used the same colors. No reason to have to different color indices use the same color.
Also when submitting graphics, please do NOT do this. It makes it harder for people downloading your graphics to actually test them out. Please, please, PLEASE name your ExGFX files the SAME name as in the sample level. If people need to use different ExGFX numbers they will change it anyways, but that's not the case for everyone. The whole idea with including.mwl sample levels in graphics submissions is to make it quick and easy for people to just download and try out your graphics. Don't make it more complicated than it needs to be.