Erik,
Have you tried to confirm with a packet sniffer (e.g., Wireshark) or a logging ACL on an intermediate switch/router that the packets are actually leaving the WCS server?
If you can confirm that, then try to confirm again on the NB receiver that the packets are arriving (you could use Wireshark right on the HP server). These two tests will hopefully narrow the problem to one specific place (WCS, NB Receiver, or somwhere in between).
Justin