I just compiled your code in MCS, then opened the .asm generated in MPLAB, selected
the 18F1220, and clicked the Quickbuild option, and it worked fine. Odd way of doing it,
but it did work.

Can you explain how you're setting up your project in MPLAB? Which version MPASM/MPLAB
you're using, etc?

Also, since it's not finding the .MAC file, I would check my path statement to make sure it
can find all files it needs.