Concert scheduler bad callback error

[jihoonl]

[INFO] [WallTime: 1412577850.404703] Scheduler :   allocated [adams]
[ERROR] [WallTime: 1412577850.413176] bad callback: <bound method CompatibilityTreeScheduler._ros_subscriber_concert_client_changes of <concert_schedulers.compatibility_tree_scheduler.scheduler.CompatibilityTreeScheduler object at 0x7f210e30d050>>
Traceback (most recent call last):
  File "/opt/ros/indigo/lib/python2.7/dist-packages/rospy/topics.py", line 688, in _invoke_callback
    cb(msg)
  File "/home/jihoonl/research/ros/turtlebot/src/rocon_concert/concert_schedulers/src/concert_schedulers/compatibility_tree_scheduler/scheduler.py", line 146, in _ros_subscriber_concert_client_changes
    pending_notifications.extend(self._update(external_update=True))
  File "/home/jihoonl/research/ros/turtlebot/src/rocon_concert/concert_schedulers/src/concert_schedulers/compatibility_tree_scheduler/scheduler.py", line 301, in _update
    reply.grant(resources)
  File "/home/jihoonl/research/ros/turtlebot/src/concert_scheduling/concert_scheduler_requests/src/concert_scheduler_requests/transitions.py", line 310, in grant
    self._transition(EVENT_GRANT, reason=Request.NONE)
  File "/home/jihoonl/research/ros/turtlebot/src/concert_scheduling/concert_scheduler_requests/src/concert_scheduler_requests/transitions.py", line 228, in _transition
    + ' in state ' + STATE_NAME[self.msg.status])
TransitionError: invalid event grant in state GRANTED