End users are unable to Authenticate.  The logs are showing the following errors

ERROR "2011-10-12 17:55:57.071 GMT+0800" 10.32.45.12 ValidationEngine 0 18505 "text=Error 18505 occurred at VSAuthOTPFirstFactorImpl.c:524. Description: VSAuthOTPFirstFactorLDAPImpl._validatePassword() -- Invalid LDAP userid, user=<User-Name>, op=authenticate, bizCont=off" Thread-3456 VSValidationEngine.c

AUDIT "2011-10-12 17:55:57.071 GMT+0800" 10.32.45.12 ValidationEngine 0 18505 "text=Access DENIED Error 18505 occurred at VSAuthOTPFirstFactorImpl.c:524. Description: VSAuthOTPFirstFactorLDAPImpl._validatePassword() -- Invalid LDAP userid, user=<User-name>, op=authenticate, bizCont=off" Thread-3456 VSValidationEngine.c

ERROR "2011-10-12 17:56:15.603 GMT+0800" 10.32.45.12 ValidationServer 0 18530 "text=Error 18530 occurred at VSValidationServer.cpp:471. Description: VSValidationServer._wokerThread() -- Invalid request received - -4" Thread-3772 VSValidationServer.cpp

You input the Base DN in the User Store to allow user to authenticate. After setting this, user can successfully authenticate.

Without the Base DN set in the User Store, search particular user from the store shown no problem, but authentication will result in error 18505.
Also make sure you are providing the correct password for the LDAP user.