cbstat/mcstat cannot access to memcached after rebalance

This may only apply to testing environment but after rebalancing btw two nodes, cbstats and mcstat cannot access to memcached's dedicated port for stats. Prior to the rebalancing, both were able to access and populate stats OK.

error message are something like below:

./cbstats localhost:12003 all
Stats '' are not available from the requested engine.
mcstat also returned: EOFError: Got empty data (remote died?). from 127.0.0.1