so im trying to get some new stuff into udk and my models arent displaying correctly. For example i made a sparse looking pine tree, it looks like this in max:

i used the first tree model technique where u just add branches to flat planes, so the material is the branches with the opacity mask on, and it is a 2sided material. When i import it into UDK it looks like this (tree is in the same position)

So somehow in the process the planes are not entirely visible and my tree looks like crap. Does udk just do this on this technique or is there something i can do? Any suggestions before i break something? Also i should clarify that i have a skylight and i always 'build all' before playing level.