Carbon-Cache AttributeError: 'function' object has no attribute 'get'

Hi,

I hope someone is able to help with this, I have searched everywhere and cant seem to find any other cases. I have just installed the graphite package from source and for the most part everything is working fine.

The problem I'm facing is when I view a graph on graphite-web I get this exception in the carbon-cache console log:

01/03/2017 09:13:22 :: Unhandled Error
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/twisted/python/log.py", line 103, in callWithLogger
    return callWithContext({"system": lp}, func, *args, **kw)
  File "/usr/local/lib/python2.7/dist-packages/twisted/python/log.py", line 86, in callWithContext
    return context.call({ILogContext: newCtx}, func, *args, **kw)
  File "/usr/local/lib/python2.7/dist-packages/twisted/python/context.py", line 122, in callWithContext
    return self.currentContext().callWithContext(ctx, func, *args, **kw)
  File "/usr/local/lib/python2.7/dist-packages/twisted/python/context.py", line 85, in callWithContext
    return func(*args,**kw)
--- <exception caught here> ---
  File "/usr/local/lib/python2.7/dist-packages/twisted/internet/posixbase.py", line 597, in _doReadOrWrite
    why = selectable.doRead()
  File "/usr/local/lib/python2.7/dist-packages/twisted/internet/tcp.py", line 208, in doRead
    return self._dataReceived(data)
  File "/usr/local/lib/python2.7/dist-packages/twisted/internet/tcp.py", line 214, in _dataReceived
    rval = self.protocol.dataReceived(data)
  File "/usr/local/lib/python2.7/dist-packages/twisted/protocols/basic.py", line 765, in dataReceived
    self.stringReceived(packet)
  File "/opt/graphite/lib/carbon/protocols.py", line 202, in stringReceived
    datapoints = MetricCache.get(metric, {}).items()
exceptions.AttributeError: 'function' object has no attribute 'get'

Would anyone be able to advise what might be causing this?