I believe I know one way to get into the situation that you describe. When you run sysprep, there is a checkbox labeled "detect non-PnP hardware". You need to check this option. If you don't, mini-setup will not do hardware detection.
I've made the same mistake. You would launch sysprep and there would be this "detect non-PnP hardware" checkbox. You don't have any non-PnP hardware in your machine, so you see no reason to enable this option. Except, as it turns out, if you run sysprep without this option checked, mini-setup will skip HW discovery altogether. Mini-setup will not only skip detection of non-PnP hardware. It will skip all HW detection, PnP and non-PnP.
In early versions of sysprep, the same checkbox was labeled differently - it just said "PnP" and you would probably have checked it without thinking. I have no idea why the labeling was changed in more recent versions, but it has certainly confused me.
Have a look at the latest version of the whitepaper. Dwonload it from droppedpackets.org.
thanks, i've discovered that running sysprep with option "detect non PNP hardware" did succesfully running the hardware detection part in mini setup, i know i was once doing sysprep without this options checked and succesfully running HII, gues we'll just have to this with this options checked now, thanks jan for your response.