While logging into luci interface as Active Directory user, login attempts fail for several times.

Issue

• While logging into luci interface as Active Directory user, login attempts fail on the first, second, third, fourth login, but may be successful at fifth attmpt.
• Error messages from /var/log/messages

Oct 14 09:41:20 hostname1 saslauthd[4177]: do_auth         : auth failure: [user=us016783] [service=luci] [realm=] [mech=pam] [reason=PAM auth error]
Oct 14 09:41:34 hostname1 saslauthd[4176]: do_auth         : auth failure: [user=us016783] [service=luci] [realm=] [mech=pam] [reason=PAM auth error]
Oct 14 09:41:35 hostname1 adclient[20949]: WARN  <gpworker> util.io.connectutil Timeout during ldap IO
Oct 14 09:41:35 hostname1 adclient[20949]: WARN  <gpworker> gp.processor Cannot load policy for hostname1$: BSDSockets::recv - Failed to received data from the socket (ret=-2)!!:  Timer expired
Oct 14 09:41:43 hostname1 saslauthd[4173]: do_auth         : auth failure: [user=us016783] [service=luci] [realm=] [mech=pam] [reason=PAM auth error]
Oct 14 09:42:00 hostname1 saslauthd[4177]: do_auth         : auth failure: [user=us016783] [service=luci] [realm=] [mech=pam] [reason=PAM auth error]
Oct 14 09:42:14 hostname1 adclient[20949]: INFO  <fd:10 PAMIsUserAllowedAccess> audit User 'us016783' is authorized

• Error messages from /var/log/secure

Oct 14 09:41:20 hostname1 saslauthd[4177]: pam_listfile(luci:auth): Refused user us016783 for service luci
Oct 14 09:41:34 hostname1 saslauthd[4176]: pam_listfile(luci:auth): Refused user us016783 for service luci
Oct 14 09:41:43 hostname1 saslauthd[4173]: pam_listfile(luci:auth): Refused user us016783 for service luci
Oct 14 09:42:00 hostname1 saslauthd[4177]: pam_listfile(luci:auth): Refused user us016783 for service luci