Yup. Elements can only go between +32 and -16 on every axis. Any points that are beyond these boundaries will cause the model to fail.
Obviously I can't tell if that's your problem since you didn't actually post the model, but that's my best guess given your description.
If you'd like more assistance, I suggest posting your model so that we can see what you've done rather than making educated guesses. OK?
I hope that helps you!
Damn. You're good at this.
Thanks a lot ^^
Now I must research how people make a whole new model for a unique boss mob.