Collision Problem

i am having a problem with collision. I have a square that the user drags through an avatar. When they collide there is no event and showCollisions has no effect.

this is the code to attach the collision box:

 collisionPoly = CollisionPolygon(Point3(x,y,z),
                                         Point3(dx, y,z),
        self.dragBoxCollider = self.dragBoxPath.attachNewNode(CollisionNode('dragbox'))
        self.dragBoxPath.setRenderMode(RenderModeAttrib.MWireframe, 2)

code for adding the collision sphere to the avatar:

 #load thest models
    #put them in the world
    model.setPos( 100, 150, 100)
#    model.setHpr(140,0,0)
    cs = CollisionSphere(0, 0, 0, 20)
    cnodePath = model.attachNewNode(CollisionNode('cnode'))

also on a side note with verbose on, when i click in the window and hold the application will crash with:

Assertion failed: imax >= 0 at line 335 of panda/src/linmath/lmatrix4_src.cxx
Traceback (most recent call last):
  File "/opt/eclipse/plugins/org.python.pydev.debug_1.0.6/pysrc/", line 729, in ?['file'], None, None)
  File "/opt/eclipse/plugins/org.python.pydev.debug_1.0.6/pysrc/", line 614, in run
    execfile(file, globals, locals) #execute the script
  File "/home/kelly/workspace/panda/src/", line 153, in ?
    run( )
  File "debtmp/usr/share/panda3d/direct/src/showbase/", line 1956, in run
  File "debtmp/usr/share/panda3d/direct/src/task/", line 821, in run
  File "debtmp/usr/share/panda3d/direct/src/task/", line 769, in step
  File "debtmp/usr/share/panda3d/direct/src/task/", line 703, in __stepThroughList
  File "debtmp/usr/share/panda3d/direct/src/task/", line 633, in __executeTask
  File "debtmp/usr/share/panda3d/direct/src/showbase/", line 1286, in igLoop
AssertionError: imax >= 0 at line 335 of panda/src/linmath/lmatrix4_src.cxx


sorry next time I will finish the pertinant section in the manual before posting a question.

ok everbody at once, “RTFM!”