Hi,
do you really need to connect through SQL to a remote database using INTERNAL user?
You might find problem connecting anyway. If you really have to, then try
setting parameter REMOTE_LOGIN_PASSWORDFILE = exclusive in initSID.ora.

Anyway if you are trying to connect from a 3rd party software. Maybe this might help.

ORA-24314: need explicit attach before initialize service context
Cause: An ociatch() was not done before an ociisc() call.

Action: Issue ociatch() before calling ociatch().