We had to upgrade our MS ODBC driver for Oracle to version 2.573.5303.00 to get this to work for us (I think, the guy that needed this and got it working isn't here right now, I'll verify later and repost if I am incorrect).
What version of MS Oracle driver are you using?
A problem is a difference between what is perceived and what is desired, that
we want to reduce (Dewey 1933)
Actually the problem is that you are using dbExecute....You need to use dbSelect. Don't ask me why this is. I find it ludicrous. Of course I also find it ludicrous that you can't have 2 DSN's open at the same time too.