Can you see the device pull an IP from DHCP? If so I would check out the registry key on the PXE server has the correct IPs: HKLM\Software\Wow6432Node\Intel\PXE
If so you can turn logging on to verify PXE is doing its job:
http://community.landesk.com/support/docs/DOC-11704
I know when upgrading I had to push the PXE Rep Uninstall, reboot, and then push the PXE Rep Install from LDMS.