flattenMedium error

code:
flattenStrongmodel= NodePath(‘flattenStrongmodel’)
flattenStrongmodel.reparentTo(render)
for name, obj in items:
cName = obj.class.name
if cName==“Guandao” or cName==“Wangguan” or cName==“Bianjing”:
obj.getNodePath().detachNode()
obj.getNodePath().reparentTo(flattenStrongmodel)
cutnum=flattenStrongmodel.flattenMedium()
print "cut nodes : "+cutnum.str()

when i run code,got an error:

AssertionError: Attempt to compute inverse of singular matrix! at lien 1812 of path\lmatrix4_src.I

Strange. This usually happens when a part of the model has a scale component of 0 in some way.

Make sure that is not the case. If it isn’t, then perhaps you could send me the model in question (you could call writeBamFile to turn the node in question to a .bam file to send, if that’s more convenient) so I could see if there is a bug in Panda.

i found the problem

some node , setscale(0,1.0,1.0),and cause problem