Helios,
I am assuming that the DN pattern is the same for both, so it should follow that the one with the higher priority goes first, unless it tries, but the call is failing to that first route. Sounds like you have the config right, would really need to see logs and just double check the config. Also make sure you have a newer software version, 104 at least as there may have been issues in the older version for this.
MikeM
mike_voip@hotmail.com