carbon: on 'send queue is full': exceptions.NameError: global name 'carbon' is not defined

aggregator.log: 17/12/2015 13:44:52 :: CarbonClientFactory(127.0.0.1:2024:b) send queue is full (1000 datapoints)

console.log:

--- <exception caught here> ---
  File "/opt/graphite/lib/carbon/events.py", line 20, in __call__

  File "/opt/graphite/lib/carbon/events.py", line 32, in <lambda>

exceptions.NameError: global name 'carbon' is not defined

17/12/2015 13:44:52 :: Exception in cacheFull event handler: args=() kwargs={}
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/twisted/internet/defer.py", line 393, in callback
    self._startRunCallbacks(result)
  File "/usr/local/lib/python2.7/dist-packages/twisted/internet/defer.py", line 501, in _startRunCallbacks
    self._runCallbacks()
  File "/usr/local/lib/python2.7/dist-packages/twisted/internet/defer.py", line 588, in _runCallbacks
    current.result = callback(current.result, *args, **kw)
  File "/opt/graphite/lib/carbon/client.py", line 114, in queueFullCallback

--- <exception caught here> ---
  File "/opt/graphite/lib/carbon/events.py", line 20, in __call__

  File "/opt/graphite/lib/carbon/events.py", line 32, in <lambda>

exceptions.NameError: global name 'carbon' is not defined

17/12/2015 13:45:02 :: Exception in cacheFull event handler: args=() kwargs={}
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/twisted/internet/defer.py", line 393, in callback
    self._startRunCallbacks(result)
  File "/usr/local/lib/python2.7/dist-packages/twisted/internet/defer.py", line 501, in _startRunCallbacks
    self._runCallbacks()
  File "/usr/local/lib/python2.7/dist-packages/twisted/internet/defer.py", line 588, in _runCallbacks
    current.result = callback(current.result, *args, **kw)
  File "/opt/graphite/lib/carbon/client.py", line 114, in queueFullCallback

--- <exception caught here> ---
  File "/opt/graphite/lib/carbon/events.py", line 20, in __call__

  File "/opt/graphite/lib/carbon/events.py", line 32, in <lambda>

exceptions.NameError: global name 'carbon' is not defined

version 0.9.14 running on python-2.7.11 on ubunut-12.04. regards