MAMEWorld Forums - Programming - Problems loading modified roms

I have modified the Vs. Dr Mario code creating my own dm-uiprg file. Other than "WRONG CHECKSUMS" it loads correctly with Mame. "WRONG CHECKSUMS" is to be expected and seems to cause no problem. However, only part of my rom image is loaded into memory. For example, the pointer to the N2A03 initial start code (at 0xfffc) and the start code itself (at 0xff00) are there and are executed correctly. However when the code tries to jump to a subroutine located at 0xbc0a there is nothing there but zeroes. It's the same for areas beginning at 0x8000, 0x8281, 0xb8ec and 0xbbfe. I've tried to find the Mame code that does the actual load thinking I might find the explanation there but no luck. I started with Vs. Dr Mario (drmario) and I'm using mamesdl 0.180. I'm fairly new to Mame. Your thoughts, ideas or comments would be appreciated.