LDAP and security groups filter

In customer AD, the 2 security groups I wanted to retrieve users from and sync to a group on FAC. This group will then be used for FortiToken mobile matching to AD username.   It works well when using "Import Remote LDAP Users by Group Memberships" If I set up the same LDAP string in "Remote User Sync Ruls" then it's empty. Logging says: "No remote users found for sync rule" VTDS_users "on remote LDAP server

Have checked a lot on FortiNet but finds no good suggestions. Those mentioned have I tested without success.