From the Active Directory where you installed PSync Agent, navigate to PSync installation folder, and go the the Logs folder, by default:
Open eta_pwdsync.log file in Text Editor
If you find the message below:
Error: ldap_simple_bind() failed while connecting to 'ldaps://<ProvServer_Hostname>:20390'.
LDAP error: Invalid credentials.
Result: Password will be out of sync with eTrust Admin.
The etapwd user password has expired or someone changed its password.