E7270 and 3040 MDT USB Media fail

Win Server 2008R2, MDT 2012 u1 (6.1.2373), WAIK (2.0.0.0), WDS  using PE x86 and x64

I have two Dell models that stop at the Wizard and display X:\Deploy. If I enter the path X:.\Deploy\Scripts\LiteTouch.wsf  I get prompted for a domain credentials window in the task sequence when using a usb thumb drive to image a laptop or pc. Dell older models I am not prompted for credentials, they simply go to the wizard and let me select my task sequence options. I used the same usb thumb drive in an E7240, E7250 (success) and same usb thumb drive with  an E7270 (prompted/fail), so I know the thumb drive is working. Previous Models working with usb media  E72750, E72740, E5420, Optiplex 580, 3010, 3020.  

Additional Info: Using the Nic boot option all models complete imaging, after credential verification, because they are completed on our network and need to have domain credentials verified.  

MDT is set up with (total control) Folder Models in Out-of - Box Drivers and Dell's latest driver package has been added to the latest model folders.  MDT has been updated, media updated. 

I have not been able to figure out why the usb key won't work with E7270 and Optiplex 3040.  

Need some help,