ORA-28538: result set not found
Cause: The client program tried fetching from a result set that is not open anymore. Many gateways will, on execution of a stored procedure, automatically close all result sets that were returned by any previously executed stored procedure
Action: Check the documentation for the gateway that you are using and see if it will automatically close currently open result sets each time a stored procedure is executed. Then check if your client program is doing anything that violates this rule. If it is, fix your program. If it is not then contact Oracle customer support
https://support.oracle.com/
http://www.oracle.com/