Hi
I Believe, You can use RSA3 for Datasources within the source system only.
if you'd created DS in APO client the RSA3 will work only in APO system for the created DS.
In BI RSA3 wont work for the DS as the source system where the DS created was APO and not BI.
Explore SCN and SAP library you'll get more info
Regards
Vinoth