Transportation zone change

Hi friends

I have created a new trasnportation zone and asingned this to the relevant countryes and customer account groups.

However when trying to update customer mastere data from one af the old zones to the new it automatically swithes back to the original. I even tryed to manipulate the table direktly, i know :-) but even here it is reversed back.

Any idea why this i shappening ?

we are on ECC 6.0

Regards

/Jacob