Distributing BW data to Mobile Clients

Hi experts,

in BW you combine workbooks and the relevant users in a role, thereby allowing those users to call up the workbooks assigned to that role in mobile sales.

Now I have the following problem while distributing workbooks from BW to CRM->Mobile Clients:

Doesn't matter which user (existing or not existing in MSA) I assign to a role, every mobile user is able to call my BW reports after I subscribed the workbooks to a mobile client! So there is no actual user restriction.

How can I restrict BW data to determined mobile users?

Thanks in advance

Mirko