First Alive Load Balancing

Hello

We have a webcam at an external location, which is streaming (on port 1935 UDP) to our firewall via public ip.

On our firewall, I created a fail over via "first alive (ICMP)", which is forwarding all ports to a ip range of two addresses. That means, if the primary server is not responding via ICMP, the stream should be forwarded on port 1935 UDP to the backup server. But when I completely shut down the primary server, which is listening on port 1935, the fail over mechanism does not work and the firewall is still sending the traffic to the primary.

Am I doing something wrong?

Thanks in advance.

Regards,

Chris