Fab,
I would check a couple of things.
1 – Make sure that the adapter is installed correctly. Have you tried a very simple example with the adapter just to verify it works?
2 – make sure you have the pre-req’s installed. SQLXML 3.0 would be the key one.
3 – What does your stored proc look like? Have you verified you are not maybe returning an unsupported type, etc? Does the stored proc work outside of the adpater?
Todd