Hey, I had this exact same problem and at first I thought it was my provider. You can see my thread at this link:
http://forum.voxalot.com/showthread.php?t=521
I found that you had to put any thing starting with an _X as the very last priority. You also noticed that the call tester (the thing where you see which provider calls are being routed to) did not pick up on this. It was saying my calls would transfered the way I wanted, however, they were not. Put the _xxxxxxx as your last priority, and that should fix it.
After reading what jorge said, he is right. I did not realize what exactly was happening, but I think both ways will work though.