Unable to add users to SSAS role

I can give user MyDomain\ABSmith access to SSDS by giving him a login and assigning him to the requisite SSDS groups/roles.

I cannot:

• Create a temporary directory on the server hard disk and assign security rights to MyDomain\ABSmith.  See THIS THREAD.
• Add MyDomain\ABSmith to an SSAS role

Also, the same service account is running SSDS and SSAS, and SSDS and SSAS are running on the same server.

So I don't get it, how can I add MyDomain\ABSmith privileges to SSDS so that he could run queries against the relational database, but not be able to add that same account to a role in SSAS (or grant that account unique privileges on a server directory).

Any thoughts appreciated.  Thanks.

--Bob