Some rom hack on Nebula emulator get me an error message

I use Nebula emulator but the one I use makes use of an ASR file modified. What I am talking about is this Nebula ver. lets me play several hacked games that can't be found in the regular realease.

So yeah, I have a lot of hacked arcade games running on this modified Nebula. Unfortunately there is one game that can't be loaded by the emulator. This is named "Rage of The Dragons Boss Hack" it's romset is named rotd+ I get this error message:

bxx-p1bin, Wrong Size. Expected 8388608 , Found 3145728
WARNING!! Some roms are missing or different

So that bxx-p1bin file found in rotd+ zip file is the cause of the problem... Is there a way to fix it?