when you boot the machine do you get the option to go into the MEBX?
I am guessing you exported the ID's to a thumb drive and booted the machine with it plugged in. The thumb drive to use can be a tricky one as well not just any thumb drive will work. the older the better I have found I have a 512meg one that seems to work on most of the machines. When you booted it did you get promtped to provision? Also putting an alias in the DNS for provisionserver and pointing it to the LANDesk core server can be done for machines that do not yet have the LANDesk agent installed. There used to be a site that had a list of USB keys that had been tested if I find it I will update my post.
In the Managementsuite directory there is a amtdicservice.log file that should have some information in it if the machines are sending in packets (hello packets) to be provisioned and if they failed or not. If there is no PID (ID) on the machine it will try and use a cert and by default there is not a cert on the core server that can be used.
Also make sure you are using LANDesk 8.8 sp3 it has the latest vPro fixes and as a post sp3 patch see http://community.landesk.com/support/docs/DOC-6725