mailman service down

Hi, After restart server the mailman service is down. After try the service restart i get following error.any help please !! Waiting for "mailman" to start ""failed. Cpanel::Exception::Services::StartError Service Status Service Error (XID dnh4mx) The "mailman" service failed to start. Startup Log Traceback (most recent call last): File "/usr/local/cpanel/3rdparty/mailman/bin/mailmanctl", line 556, in main() File "/usr/local/cpanel/3rdparty/mailman/bin/mailmanctl", line 391, in main lock = acquire_lock(force) File "/usr/local/cpanel/3rdparty/mailman/bin/mailmanctl", line 215, in acquire_lock lock = acquire_lock_1(force) File "/usr/local/cpanel/3rdparty/mailman/bin/mailmanctl", line 203, in acquire_lock_1 if not force or qrunner_state(): File "/usr/local/cpanel/3rdparty/mailman/bin/mailmanctl", line 187, in qrunner_state os.kill(pid, 0) OSError: [Errno 1] Operation not permitted mailman has failed. Contact your system administrator if the service does not automagically recover.