Cannot wrap stored procs in transaction via sql server link

Hi List;

We've setup a sql server link to a postgres db via the postgres ODBC
driver. queries work fine except we see this when trying to embed a stored
proc within a transaction:

[OLE/DB provider returned message: Unsupported connect attribute (Set)]

OLE DB error trace [OLE/DB Provider 'MSDASQL'
ITransactionJoin::JoinTransaction returned 0x8004d00a].

Anyone have any ideas how to debug/resolve this ?

As always, Thanks in advance for your help & support...