Cannot update database with MTS/Oracle8i??

[densorz]

I've developed a 3-tier webservice (ASP/COM+/ORACLE) that after some troubles now works fine when firing select statements on the database. However when trying to fire an insert or update statement I get errors. I think it's because of the value assigned to the property MTSTransactionMode in Visual Basic(version 6). What should this value be?

In COM+ I declared for every thread several classes.
MGR class: entrance
DAN class: executing select statements (This works fine!)
DAT class: executing insert and update statements

The DAN-classes have value 3(=UsesTransaction) and the DAT-and MGR-classes have value 2(=RequiresTransaction).


Here are the errors:

If I change MTSTransactionMode for DAT and MGR to 0, 1 or 2:

Error 00013 : 06-03-2006 16:18:07 
  - Description: addRequest(DAT):   - 'Type mismatch'
  - Line Number: 5

If I change MTSTransactionMode for DAT and MGR to 3:

Error -2147168246 : 06-03-2006 16:22:28 
  - Description: GetConnection error: 'Provider=OraOLEDB.Oracle;Data Source=demo8;User Id=arnhem90;Password=arnhem90' - 'De nieuwe transactie kan niet worden opgenomen in de lijst voor de opgegeven transactiecoördinator.'
  - Line Number: 50
 
Error 03709 : 06-03-2006 16:22:28 
  - Description: getTabValue: 'De verbinding kan niet worden gebruikt om deze bewerking uit te voeren. De verbinding is gesloten of deze is ongeldig in deze context.'
  - Line Number: 10
 
Error 00091 : 06-03-2006 16:22:28 
  - Description: addRequest(MGR): 'Object variable or With block variable not set'
  - Line Number: 50

Thanks for the help provided!