Issue in registering DS repo in CMC

DS 4.0 SP4

BI 4.0 SP5 Patch13

We migrated DS Repos from Oracle 10g to 12c.

Now I am trying to register that repo with new connection string , I am getting and error " There is a problem to connect to repository. Repo connection failed."

I am able to register with Job server, but not via CMC.