Faces not getting rendered

Hi to all, im just getting started with 3D Max 9 + oFusion, im a programmer and i have very little idea about 3d modeling and stuff, so please understand.
So, i have an issue with the exported meshes, unfortunatelly i dont know how to search for a topic about this.
Basically im getting some faces of the meshes not rendered, better see an image:

OK - 3D Max Perspective


Wrong - oFusion (Front)


OK - oFusion (Back)


im using oFusion CE (very interested to get the pro version) without the scene loader, only the .meshes and materials are loaded into a custom scene format.

You need to disable backface culling (to enable double side rendering) in the material

You need to disable backface culling (to enable double side rendering) in the material

Thank you Lioric! In case some beginer end up in this post, i did:
Select the face or object, press M.
Look for Shader Basic Parameters and check 2-Sided.
That did the job, thanks a lot.

By the way, anyone know how to use the Atach option of max to paste togheter different objects? Because now im doing Select->Mesh Select, then i do right click and Atach, then i click every object individualy, but i want to add several parts in one shot... if i click Atach List i get all objects of the scene, and i dont know wich one to add.