Locator : region problem

I'll simplify things.

Running a locator L

Running four cache servers A and B

A and A' have replicated regions AA and AB

B and B' have replicated regions BA and BB

I connect to L as a client (client-cache) with a proxy to region AA. Sometimes I get connected to A or A' and it works, sometimes I get connected to B or B' and my first PUT fails.

I didn't see anything that said the regions need to be in ALL the cache-servers. Is this normal, expected behaviour?      

Edit: Or are we ~really~ expected to define a server group for every region so we don't need them everywhere?