Pinkvenom they're not added properly within DBP ... if you add them they generally don't attach unless they are 16x16/32x32 4-Bit 16Colours
I'd go out on a limb and say there is a major bug with this and not one that is likely to be fixxed anytime soon, and i'm not sure if its with the compiler or the Editor - although when i was using my own editor for a while i don't remember them giving me any trouble.
if i were you i'd just leave it for a while or move all of the standard icons out of the compiler directory and replace with the icon you want

Or a Resource Editor, but i dunno which would be good
I pride myself that i don't kill...

well not without a good reason