FF Level Editor: Recompressed WoR mini-map exceeds allotted space.

First off, hello there, this is my first post on the forums and I hope I can learn a thing or two from you all.

Okay, so I've messed around with most of the programs just to see what does what and as I was making a map in the Level Editor just for fun, I noticed this message popping up every time I saved it: Recompressed WoR mini-map exceeds allotted space. The WoR mini-map was not saved. Through this procedure, I am unable to save my map. The ROM I originally used wasn't clean, so I re-downloaded a clean ROM to make sure it would work and the same message came up; even if I didn't change anything, saving would result in this message popping up. If the info on my ROM means anything, I'll post it here:

ROM Name: FINAL FANTASY 3
Header: False
Checksum: 0x9606 (FAIL)
Gamecode: F6
Ov. Map Exp. Bank. 0xF1

Map editing will be rather important for what I'm planning on doing, so I'd really appreciate if someone could find the answer for me.