Have you tried connecting in the manner I first suggested?
sqlplus /nolog
connect username/password@service as sysdba
This is the way that Data Protector tries to log in to the Oracle database. You cannot use any o fthe know shortcuts, like
connect / as sysdba
or
connect username/password@service
If you can commect this way
connect username/password@service as sysdba
and yet, cannot connect using the DP GUI to configure the instance, you will probably need to open a case with the response center