oracle database credential test fails

Hi.

I have BE 2012 on windows server, and RALUS installed on oracle linux 5 with Oracle 11g2.

All credentials tests suceeded except on oracle database credential fails.

root credential on linux server             ==> test succeed

oracle credential on ocracle instance  ==> test succeed

sysdba credential on oracle database ==> test fails

due to this I'm unable to connect to the  database to perform a backup.

Any Ideas?