ACD multiple Queue longest waiting

[Utreg]

In a multiple Queue situation a call to 2630 arrives earlier at an agent then a call to f.e. 2650 does, the waiting time is longer though:

ACD 2650 waiting 3 lwait 02:30
ACD 2630 waiting 1 lwait 00:45

the situation:
Mainnumber is a voicemenu with 5 choices which queue to an ACD (2610 to 2650).
All calls from and to the menu are routed via CCR
All sets are programmed with KEY 0 ACD 2610
All the routing in the scripts is done withe the same priority.
All agents login with the same priority.
All callflows to and from the menu are setup the same.

Any ideas where what to check to have the longest waiting of ALL Queues treated first by an agent?
Thanks,
@win

 

[Utreg]

Additional info: We rebooted the CCR system. This had no effect.