Errors on Python Collector Plugin

I am trying to create a plugin for the python collector to poll some data from a Citrix NetScaler via a REST API.

I have successfully created a new device class , modeler plugin, and the components that I want to monitor.

After writing a plugin, I see a number of errors that I am unable to troubleshoot:

2014-03-10 08:46:01,900 DEBUG zen.collector.scheduler: Traceback (most recent c:
Failure: Products.ZenHub.PBDaemon.RemoteException: : Traceback (most recent cal:
File "/opt/zenoss/Products/ZenHub/PBDaemon.py", line 85, in inner
return callable(*args, **kw)
File "/opt/zenoss/Products/ZenCollector/services/config.py", line 218, in rems
devices = self._getDevices(deviceNames)
File "/opt/zenoss/Products/ZenCollector/services/config.py", line 204, in _ges
devices = self._prefs.devices()
File "/opt/zenoss/Products/ZenRelations/ToManyRelationship.py", line 71, in __
return self.objectValuesAll()
File "/opt/zenoss/Products/ZenRelations/ToManyRelationship.py", line 174, in l
return list(self.objectValuesGen())
File "/opt/zenoss/Products/ZenRelations/ToManyRelationship.py", line 182, in >
return (obj.__of__(self) for obj in self._objects)
AttributeError: 'NetScalerDevice' object has no attribute '__of__'

Any ideas on how to figure out what is happening