I had this issue, i had to upgrade 0.9.12 to 11.5.
I ran a gpo to upgrade the client.
Used orca to edit the msi file and add the ip address of my fog server. Then created GPO for installing software and selected the MSI.
The client updates, but needs a reboot for the services to startup.
Also had to update my images to include the new client.
Hope this helps
FOG with sysprep: https://wiki.fogproject.org/wiki/index.php?title=FOG_Client