Netboot - Cannot get client to select image yet the server is BSDP INFORM'ing ok

We are at the stage of deploying to our 8 labs and we cannot netboot any of the machines... We have changed over servers from 10.8 to a 10.7 and still have no joy.

I'm running 1.7.4 Server and i cannot get passed the BSDP ACK stage!?!

This is what i'm seeing in system.log:

Aug 16 10:16:40 adt-management bootpd[5202]: NetBoot: [1,c8:2a:14:1f:df:e6] BSDP ACK[LIST] sent 10.30.6.228 pktsize 300

Aug 16 10:16:40 adt-management bootpd[5202]: DHCP INFORM [en1]: 1,c8:2a:14:1f:df:e6

Aug 16 10:16:40 adt-management bootpd[5202]: reply ciaddr 10.30.6.228

Aug 16 10:16:40 adt-management bootpd[5202]: ACK sent 10.30.6.228 10.30.6.228 pktsize 300

Aug 16 10:16:40 adt-management bootpd[5202]: service time 0.000588 seconds

Aug 16 10:16:43 adt-management bootpd[5202]: BSDP INFORM [en1] 1,c8:2a:14:1f:df:e6 arch=i386 sysid=iMac12,2

As you can see the client is iMac 12,2 - 27"

The server is an old Xserve 1,1 2x2 Dual-Core Intel Xeon with 6GB RAM

Any pointers would be a huge help.

Kind regards,

Sam.