Can’t create NetInstall image (maybe 10.6.6 is the problem?)

I haven't done this in a long time, so maybe I'm missing something blatantly obvious. I just got a handful of laptops and a bunch of iMacs in that all need to get a standard install (will actually create two installer images), but as the latest models they won't work with the last images I had made (usually I just get one or two machines at a time, but we haven't gotten any in quite a while. so now there are a bunch) now is the time to revamp. I figured setting up a NetInstall image would make the most sense, giving me more flexibility later. I have a 10.6.6 Mini Server dedicated to this, so the only thing I needed to do was create the image using System Image Utility. Connected a baseline install on a MBP in target mode to the Mini Server. Open SIU, but the only options are NetBoot and NetRestore- is it possible the SIU tool can't yet recognize the 10.6.6 as a valid source image for NetInstall? Or am I missing something altogether different?