Looking through the uploaded models, I found many assembly models that are actually useless because the assembly parts are missing. While uploading an assembly model created with Solidworks, Slid Edge, Catia, NX or other MCAD systems, you should be aware that the upload of the .asm (or .product) it is not enough. You must upload also the part files (.par or .CATPart) in order to make the full assembly visible and usable.
In order to check if the upload was ok, just open the 3D view of the model by selecting the link available in the file page
If some part is missing, you will get the following warning