Panda PhysX

I am trying to create a convexmesh nxb file for an object within a map that I created with 3dmax. Heres the code:

import direct.directbase.DirectStart
from pandac.PandaModules import Filename
from libpandaphysx import PhysKitchen

fname = 'map01'

map=loader.loadModel( 'models/%s.egg' % fname )
np=map.find("*/object")

status=PhysKitchen( ).cookConvexMesh( np, Filename( 'models/%s.nxb' % fname ) )
print 'Kitchen status for mesh:', status

I get the following assertion:

If it can’t find the object it gives an assertion that says something about isEmpty(). So I believe that it does find the object but its not in the same ‘form’ as when using the loader to load a model and then the kitchen says that the mesh is missing. I have also reparented the found nodepath to the render node and the object does get rendered, which means that the mesh can’t be missing.

Any idea how I can get it to work or a reason why its not?