Imaging Server Not Found

We have three different Dell models in our offices.
GX270, 280 and 520.
I set up a policy to send the right image down and this works perfectly on
the GX280 and GX520. However on the GX270, we get a message saying 'Imaging
Server not found'
Going through the maintenance mode imaging, and choosing restore image, the
IP address is defaulting to a test server on a test tree. I unloaded all
the zen services but it still insists on looking at it. The 280- and 520
pick up the proper server without problem. The 270 was previously imaged
using the proper server.
Our DHCP server is setup to point requests to the correct server.
Anyone know what I've missed?