Python Orange: orngMDS package error "TypeError: argument 1 must be (unspecified), not orange.SymMatrix"

Question

Hi! I'm trying to use orngMDS package from http://www.ailab.si/orange/doc/modules/orngMDS.htm
Here is my code:

distance=orange.SymMatrix(len(codes))    
for key,value in normalized.iteritems():
   parts=key.split('\t')
   distance[codes[parts[0]],codes[parts[1]]]=1-value
mds=orngMDS.MDS(distance) 

And I get the error:

mds=orngMDS.MDS(distance)
Traceback (most recent call last):
File "", line 1, in
File "orngMDS.py", line 92, in init
self.mds=orangemds.MDS(distances, dim, **kwargs)
TypeError: argument 1 must be (unspecified), not orange.SymMatrix

My system: ubuntu-9.10 + python 2.6