Blender - Multiple Materials, export to FBX


I have a small question. I just started learning to model and how to put my models in UT. It works fine as long as I only have 1 material in my Blender model. Once I have multiple materials (for instance wood for a desk and metal for the handles) exporting to FBX results in an error Index out of bounds (which afaik from programming, is that an array is causing an issue). Removing the second material fixed the issue. Is there some way to export with 2 materials? As I would like to reuse the metal texture and wood texture in other models as well, without having to create a specific UVMAP for my desk.