System.Transactions.Transaction Promoting To DTC? Why?

Taht is my code. I have a defined common transaction.

In my call path, I use:

using (IDbConnection connection = GetConnection ()) {

retval = q.Find (connection, out DataParticleList);

connection.Close ();

}

DetermineDataParticles ((DataParticle[]) DataParticleList.ToArray (typeof(DataParticle)));

And then, in Determine DataParticles, I do:

using (TransactionScope scope = new TransactionScope (_Transaction)) {

using (IDbConnection connection = GetConnection ()){

again. As both are using a TransactionScope that - uses the same transaction, and as the first connection has been closed - should the whole thing not reuse the same connection? GetConnection () has the same connection string.

I get a promotion to DTC in the second GetConnection (). That indicates that a new connection is being opened (and attached), and not the first one being used. Any hint on why that is? What can I change for this? I would really like this not to be promoted upward to DTC. It makes no sense to me.