Hi @KS_23
From what I've searched, a common reason for the error "'GETREGIONGROUPS' is not a procedure or is undefined" to appear is a typo, or it's actually a stored function, not a stored procedure, check those. For more about these, you can refer to this link.
According to your description, you have adopted the OLE DB connection type, maybe you can check whether the connection steps are correct, you can refer to this document: OLE DB Connection Type (SSRS).
I'm sorry that I don't know much about oracle, I can only provide you with this information, maybe you can go to oracle-related platforms for help.
Best regards,
Aniya