Domain joins depend on your Domain. No OU location speficied and no Computer account precreated and If your Domain Admins have disabled the default Computer OU in AD will cause failure.
Also Vista/Win 7 no longer support failure Domain join stop in Sysprep.
Sugestion as atest. Pre Create the computer account in AD OU and set for a <your domain>Domain user to join. This als requires a domain account and Password in the unattend.xml under the AutoJoin catalog item.