The problem was that the normalizer was returning each value as a tuple which we were then appending to a list, so it looked like [(u'value1',), (u'value2',),...]. If there was a single value we could end up adding a tuple to a list which would fail. Additionally python-ldap doesn't like lists of lists so it was failing later in the process as well. I've added some simple tests for setattr and addattr. ticket 565