BATTLE BACKGROUND HELP!

Okay, so I got myself a wierd problem...

I'm using RM2K (an antique, I know), and I'm having this strange problem. In my newest map, the random encounters simply will not accept the battle background I set for it. Whenever a battle starts, it just picks up the background based on the terrain. So no matter what I try, all the battles are in the grasslands background. What the hell is going on?!

Can anyone help me, here?!

The map's properties.

Yes and no, which is why this makes zero sense. I've done this many times before...

Yeah, for some reason, it's working on every map I make now BUT that one. Glitch, I guess, I dunno. ANyway, I'm just not putting any encounters there. Sorry for the trouble!