What I typically do once I've exhausted the basics (services running on my PXE proxy, IP address on the PXE client is in the correct subnet, etc.) is fire up Wireshark on my PXE proxy and see if it gets the broadcast packets. I noticed that seemed to be a rather large subnet so perhaps the broadcast packets aren't getting picked up in time.
I would shutdown the other proxies unless you can capture and filter on all three easily. Next step would be test on an isolated network.
Probably is a incompatibility with Windows 7 (my LDMS is 8.8 SP3).
I remove the PXE representatives, deploy in a Windows Server 2003 and functioned normally.
Yes running on Windows 7 would have been important information to include in the first post.
The PXE Representative has never been been tested on windows 7 yet and so that feature is in an unknown state on Windows 7.