There are two issues with using Business Units like this.
First of all, the query that you specified includes only Organizational Units in the Business Unit. In other words, your Business Unit includes only the Organizational Units, the name of which contain Service, but not the users located in the OUs.
Secondly, until an object is actually created in AD, LDAP search filters cannot be applied to it, and thus objects that haven't been created yet cannot be included in Business Units by query.
Can you describe your task in more detail so we could help you find an appropriate workaround for it?