Please check below points to troubleshoot an LDAP Lookup plugin
1] If the plugin does not save correctly, verify the configuration.
Before using the LDAP Lookup Plugin you should test the connection to the LDAP server. You can use a lookup tool such as the Softerra LDAP Browser to help confirm that you have the correct fields defined.
2] Make sure that the plugin is enabled.
3] Make sure that you created the Custom Attribute definitions.
In particular, check the attribute mapping. The attribute names must be identical.
4] If you made changes, or edited the lookup parameter keys, reload the plugin.
5] Select Incidents > All Incidents for the detection server you are using to detect the incident.
6] Select (check) several incidents and select Lookup Attributes from the Incident Actions drop-down menu. (This action looks up attribute values for all incidents for that form of detection.
7] Check the Incident Snapshot screen for an incident. Verify that the Lookup Custom Attributes are filled with entries retrieved from the LDAP lookup.
8] If the correct values are not populated, or there is no value in a custom attribute you have defined, make sure that there are no connection errors are recorded in the Incident History tab.
9] Check the Tomcat log file.