That explains, We could have got here before.
Probably you missed the para
The Microsoft Windows Vista feature, "User Access Control" (UAC) blocks local administrative accounts from remotely accessing remote administrative shares such as "C$" and "Admin$." To use the "Push Deployment Wizard Tool" in this scenario, use a "Domain Administrative" account if the target client computer is part of an "Active Directory" domain. Remote client installation also requires elevated privileges to install
from the article posted above.
But you got there:)