Nagios checks through F5 load balancer



I am trying to monitor a service that is running on one of two hosts that sit behind an F5 load balancer. I am using check_nrpe to connect and check_procs to check on the process. The check_procs looks for a single instance of the process on one of the boxes. The process should only be running on one box at any time so alerts should be generated if there are 0 or 2+ processes running. I was able to successfully get this going using a logical IP in a Sun Cluster configuration but the F5 has me stumped. The check_procs seems to be trying to run on the F5 device itself rather than the backend servers. Please point me in the right direction.