ERROR_OPERATION_FAILED --117

I am getting the 117 error when i tried to execute the following command so please let me know what is the real cause of it and what needs to be done to fix it( i am new to scanner SDK integration) . I am want to send back a beep sound back to Scanner , but not able to do that  because of the above error. I have enabled HID_KB_PUMP_SETTINGS in config file so please see the below attached screen shot . I am using USBHIDKB mode to send back the message to scanner .My Scanner model is LS4278

   int opcode = 6000; // Method for Beep the beeper

            string outXML; // Output

            string inXML = "<inArgs>" +

            "<scannerID>1</scannerID>" + // The scanner you need to beep

            "<cmdArgs>" +

            "<arg-int>4</arg-int>" + // 4 high short beep pattern

            "</cmdArgs>" +

            "</inArgs>";

            cCoreScannerClass.ExecCommand(opcode, ref inXML, out outXML, out status);