Call of Duty models keep disappearing (LOD Issue?)

[jiggy22]

Anybody here who's familiar with working with asset manager and maya for Call of Duty World at War? I'm facing a really annoying issue with several of my ported perk models. I have no idea if it's an issue with the LODs or what, but whenever I walk up to a ported model, it just disappears. If I look down enough, it reappears, but looking back up at it causes it to disappear again. I actually tried using multiple LOD models and setting proper distances for one model, but that did nothing. One model worked completely fine though (I have no idea how or why), but when I try the same exact thing for the other models, they just keep disappearing. I've been trying to ask for help with this on the UGX forum, but that place has been pretty dead for the past few days, so I'm trying my luck here instead. Anybody here know what I'm doing wrong?