Linked Server Via ODBC And Stored Procedure

Hi

We're trying to use call a stored procedure to update information in a
remote Ingres database. We've linked the server, and can read
information using SELECT * FROM OPENQUERY (..........), but we can't
find a suitable syntax for executing a procedure.

Using SELECT * FROM OPENQUERY and passing the EXEC statement in a
string gives a message about not returning any columns - not surprising
as there aren't any, and trying to execute the procedure more directly
using:-

EXECUTE abrs..vipdba.ats_reader_pi0 ........

Gives the error

Could not execute procedure 'ats_reader_pi0' on remote server 'abrs'.
[OLE/DB provider returned message: Parameter type cannot be determined
for at least one variant parameter.]

Any bright ideas?

Chloe