Oracle Error Message
ORA-28557: unknown string for database link to non-Oracle system
Reason for the Error
When attempting to connect to a non-Oracle system through a Heterogeneous Services database link, the agent supporting this non-Oracle system failed to return FDS_CLASS_NAME and/or FDS_INST_NAME. ORACLE requires these names to configure the heterogeneous database link.
Solution
Contact the DBA to check setup of the connection and the Heterogeneous Services agent.