[Max]Parts ripped out Bug

Hi there,

iam currently converting CSS mods to GTA SA.

Now iam stuck and running out of ideas cause my Ingame model looks way different as in max..

Here we are a max render of my model:


And here it is ingame, pay attention to the left side of the scope. seems like there are parts ripped out :S


After importing my recently exported .dff it looks like that, vertex are there where they didn't were before -.-


Anyone got any clue what i do wrong? Like press this button or attach this..
Ive made the whole import again, still the same parts missing.. thats weird..

Thanks in advance for any help

hmm can you upload the 3ds format one? i got used to 3dmax so probably i can fix it