I get a "Concurrency Violation - UpdateCommand affected 0 records" when i update a Dataset twice or more. (Im working in deconnected mode)

The first time, everything is fine, second time i get the error.

If i refill my dataset with the DataAdapter after every save, everything is fine. But i want to reduce the access to database time, so i dont want to reload my dataset each time i do an update ! It is possible to avoid that ?

Im using VB .NET 2003 with Oracle 9I database.

Thank for your help !

Sebastien