Active Directory Logon / Site Link Bridge Issue

Dear NC,
i have an issue with users in different Locations, to explain easyest here is a little network diagram:

So, as one can see, i have 4 Locations, one is the Headquarter.

The Target Goal is: Users in Location C must Logon with Domaincredentials from Sub.domain.tld from Location A.

Location HQ, A and B are fully routed, Location C has only a route to Location B.
Every Location has at least one writable DC with GC ans DNS Server installed.

I have the following site links:
HQ<>A
HQ<>B
A<>B
B<>C
and also a Site Link Bridge with "A<>B" and "B<>C".

Unfortunatly Users cannot logon in Location C with sub.domain.tld Domaincredentials from Location A.

Need a bit help, thx :-)

-Bernd