it's a tileset malfunction, if the maps you're connecting are using different SECONDARY tile-sets, it can often cause errors no matter what you do with warps. if you HAVE to use two secondary tile sets, make use one map or the other doesn't use them.
the other error i've ran in to is editing gatehouses, everytime i change one, I'll enter it, and the screen is black.
essentially, don't edit gate houses, and don't mix tilesets from map to map.
hope this helped.
Alright, I've recently been trying to insert a world map, but to no prevail. every time it ends up some thing similar to this:
I'm locating it in UNLZ.GBA, editing the image, writing to ROM, re-building in NTME, then writing the RAW to the ROM. then I'm changing the original HEX with the new one. but it's just not working.
This is the map I'm trying to insert: