fbx revit is incopatible whith D5
In this scene, the room is a skp file and the material ball with the fabric on top is a fbx file imported into the scene.
So the fbx file works perfectly.
Can you post your file so i can take a look.
Use lumion plugin to export a collada file (.dae) from revit.
Then open in Blender and convert it to a .d5 file!
Or use simlab converter to export .skp from revit, but free trial is only 15 days and results are ot as good as the solution above.