Have you tried several materials? Especially procedural materials or simply basic ones. Pure red for example. To see wether it has to do with the object or anything else. And how do you apply the materials? Drag and drop or by right mouse click on the object name in the world browser to apply the material through that? Try that and report the results please. Finally, if you want to, send me the object to let me see what is going on. Not that i probably can help too much, but sometimes four eyes see more than two.

One day your ship comes in - but you're at the airport.