Action server callback not working

I'm implementing the action server below:

  class NavigationServer:

def __init__(self, name):
self._action_name = name
self._as = actionlib.SimpleActionServer(self._action_name, rodain_get_directions.msg.NavigateAction, execute_cb=self.execute_cb, auto_start=False)
self._as.start()

def execute_cb(self):

For some reason my callback function is not being called and messages aren't written in log file. Any idea why it is happening. I have a launch file that starts both client and server sides and client works fine.
Are you assuming that execute_cb is not being called just because you don't see the logs? If so, are you running the roslaunch with --screen to force all the logs to be sent to screen? In the launch file would be output="screen".