HaloMods "Classic" Read-only Archive

I tried to give my warthog a new paintjob, just as a test more than anything. I opened up the tags\vehicles\warthog\bitmaps\warthog.bitmap file, did a printscreen of the image, and proceeded to edit it and saved it as a tiff (made sure it was 512x512). I used tool to convert that tiff to .bitmap and...