A common problem is that if your global_names init.ora parameter is true.
This means all link names should have the same name as the database you
are linking to. Either change the parameter or change the link name.

I.E.


ALTER sesion set global_name = false;
But you should change it in your init.ora file...

or just do
CREATE DATABASE LINK aafnbdbo CONNECT TO aafnbdbo IDENTIFIED BY
xxx USING 'aaprod';

Not sure if that's the probolme in this case but its a common one...

You should ensure the new service name is in the tnsnames.ora on
the server but you said you checked that rigth?