ORA-28558: HS_FDS_CONNECT_STRING undefined for non-Oracle system
Cause: A database link to a non-Oracle system had no HS_FDS_CONNECT_STRING initialization parameter in the ORACLE server's data dictionary for Heterogeneous Services. Without this parameter, the connection could not be completed
Action: Contact your DBA to verify correct setup of an HS_FDS_CONNECT_STRING entry in the ORACLE Heterogeneous Services data dictionary
https://support.oracle.com/
http://www.oracle.com/