Also, I think it would be important to know if it were one of these two flavors:
1. The "plain" protocol which works on top of TCP and uses port number 1935
2. RTMPT which is encapsulated within HTTP requests to traverse firewalls
If it were the first flavor, I think you would have to reconfigure the SP recorder to record whatever interface tool you use with your application, and make sure you specify the correct port.