Th error comes just after sepciying the DB HOSTNAME,PORT,SERVICE,PASSWORD of SYS
"ERROR: SQLException null Resultset Cause: Verifying whether database is valid for this install, using the given credentials has failed. Possible Reasons: 1. Credentials provided may be incorrect 2. Listener may be down 3. Database may be down Recommendation: Check whether it is because of the above said possible" I've connected using the credentials.