GMAP problems...

[JkWhoSaysNi]

I have a gmap overworld (pretty large, 16x16 levels) but there are a few problems:

1. Signs dont work.
2. NPC's dont show up, mostly. Ones using setimg work but most with any kind of scripting dont. showcharacter npcs never show up.
3. Bombs dont work.
4. Horses dont show up but you can walk over the spot where they're supposed to be and it will put you on them.
5. Arrows work, however if you shoot, the arrow goes across one side of the level and comes back on the other. I checked and the edge levels are not connected.

Any ideas how I can fix any of these problems?
I'm guessing they're all related though.