Ok, just an update for my situtation. I can clearly see in the paramets tab that my object has all the parametrs switched off, but even if i switch them on the selected texture is the "default" so I guess that's why it's shown as grey or black (i think). What's the solution, I am missing textures? And how can i find the specific texture this object has?
If I switch on one of this parametrs and select one of my textures, then the object shows correctly in my 3d window. But what should I do, download only objects from which I have the Textures?
Update2: The more I read the more I understand that it's not something I do wrong. Probably it's a fault of the uploader who didn't upload the gsm file correctly (probably converted it) from 3ds and didn't make sure the textures can be used by others