Hi,
-When you created configuration , on Oracle login infortmation to primary database , what user name do you use?
-check file cell_info on cell managaer, check if the linux client has an -oracle8 reference.
-from oracle server Post output for:
•SQL> select * from v$pwfile_users;
Also , are you sure the comuniation is fine? on both ways? ping ? telnet?
Regards