Hello Rajesh,
In Back-End system after Creating RFC Destination For Outbound Queues in SPRO by maintaining all the details regarding the GW System by selecting Classic With bgRFC as transfer protocol, have you maintained Gateway Settings under SAP NetWeaver Gateway Settings?
Where you need to maintain Destination system ( Your GW system ID ),Client,System Alias ( Which you have created in GW Hub system ) and RFC Destination ( which you just now created in the above step ).
Please check this.
regards,
Ashwin