[Q] SET ROLE not working in a SQL Passthrough Query

I'm having a problem issuing a SET ROLE command through ODBC from an MS-Access app. The idea is for a user to have no privileges at default but have password-protected application-specific roles assigned. The app then issues a SET ROLE command using the password (which the users do not know) to enable the privileges that the user needs to use the app.

It looks like the SET ROLE command is getting through to the server, it's just not working. Here's the ODBC error message I get:

[Oracle][ODBC Oracle Driver][Oracle OCI]ORA-01924: role 'HR_MSACCESS_USER' not granted or does not exist. (#1924)

This makes no sense to me since the role DOES exist; I can successfully issue the exact same SET ROLE command from within SQL*PLUS, and even from the ODBC Test utility.

Can anyone shed some light on this?

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