cas error?

I'm getting this error for cas (using couchbase 1.8 and the python client from github):
>>> c.client.get('test')
(1, 26, '1')
>>> c.client.cas('test', 0, 1, '1', '1')
Traceback (most recent call last):
File "", line 1, in
File "/usr/local/lib/python2.6/site-packages/couchbase/client.py", line 227, in cas
return self.mc_client.cas(key, exp, flags, oldVal, val)
File "/usr/local/lib/python2.6/site-packages/couchbase/couchbaseclient.py", line 861, in cas
return self._respond(item, event)
File "/usr/local/lib/python2.6/site-packages/couchbase/couchbaseclient.py", line 832, in _respond
raise item["response"]["error"]
struct.error: cannot convert argument to long
or
>>> c.client.cas('test', 0, 1, 1, '1')
Traceback (most recent call last):
File "", line 1, in
File "/usr/local/lib/python2.6/site-packages/couchbase/client.py", line 227, in cas
return self.mc_client.cas(key, exp, flags, oldVal, val)
File "/usr/local/lib/python2.6/site-packages/couchbase/couchbaseclient.py", line 861, in cas
return self._respond(item, event)
File "/usr/local/lib/python2.6/site-packages/couchbase/couchbaseclient.py", line 832, in _respond
raise item["response"]["error"]
couchbase.couchbaseclient.MemcachedError: Memcached error #2: Data exists for key