Problem starting Add-On via Citrix

We're trying to start an add-on in B1 via a Citrix connection, but we get an error: "Connection Failed. Retrieving the COM Class factory for component with CLSID...."

The funny thing is that the add-on runs fine on the Citrix machine directly, it works fine on a fat client, and it works when someone is running a desktop via the Citrix client. The problem occurs when the users log in to the application as a Citrix application (instead of going directly through the desktop).

Any ideas?