scenery- collision model not working

[an emu]

for some reason my collision model isnt working for two scenery objects i made. i have a couple scenery objects that work like they are supposed to, but i cant see anything different that i did. is there anything special i should do when exporting it, like does the object need to be called collision-geometry? also with these objects, in sapien they are only visible from a certain angle while the ones that work are visible all around