03 montana door locks

My 98 transport had a feature that would let you lock or unlock all the doors from any door key by holding the key in the lock or unlock position.

According to the owners manual the 03 should do the same. Took it to the dealer (under warranty) to have it fixed. After they changed the settings on all the programable features they told me that it must not have this feature (it was not a programable feature on the 98 it was just there). Now out of warranty asked another dealer if this model had this feature (gave him the vin #). They said that the only way to know is to put car on a scanner.

Is there anoher way to tell, and if it is not working where do I start looking for the problem? 

Thanks for the reply.

It has a factory content theft system that is set to arm with the remote only. Are you saying that it will not unlock all doors with the key in the door if set that way? I have tried it when disarmed with no success. When i try with it armed the alarm sounds and it can only be stoped with factory remote.