This error can occur if you do not check the option "Authentication Required to search LDAP" in the Authentication required section. Please make sure to add the checkmark for this option and try again. If you still see the error after enabling Authentication Required to search LDAP then I would try doing a simple bind to the AD server using an LDAP browser with the same DN you are using in the PCS LDAP server settings to insure that the credentials work for the specified DN. You can run an LDAP browser from the AD server itself by launching ldp.exe at a command prompt then logging in with the same DN and credentials.
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