rebalance failed with reason {badmatch,wrong_rebalancer_pid}

rebalance after failover 2 nodes (replica=2) is failed:
2012-09-13 15:45:40.491 ns_orchestrator:2:info:message(ns_1@10.3.3.58) - Rebalance exited with reason {{bulk_set_vbucket_state_failed,
[{'ns_1@10.3.3.68',
{'EXIT',
{{badmatch,wrong_rebalancer_pid},
[

{janitor_agent,set_vbucket_state,7}

,

{janitor_agent, '-bulk_set_vbucket_state/4-fun-0-',4}

,

{misc,'-parallel_map/3-fun-0-',4}

]}}}]},
[

{janitor_agent,bulk_set_vbucket_state,4}

,

{ns_vbucket_mover, update_replication_post_move,3}

,

{ns_vbucket_mover,handle_info,2}

,

{gen_server,handle_msg,5}

,

{proc_lib,init_p_do_apply,3}

]}