See attached debug.log for details. I successfully backed up a linux, vmWare VM using Snap Creator and the vmWare application plugin. When I restore using Snap Creator, the first thing it does is power down the VM. It then confirms that the NetApp configurations (cluster, vserver, volume/datastore) are correct. Then it tries to connect to the VM's Snap Creator agent. That fails, of course, because Snap Creator already powered down the VM.
Re "The Snap Creator agent should not be installed within the same VM that you are trying to backup", it's not. The agent involved in the restore is on a separate VM.
I spoke yesterday with a resource at NetApp who found the cause by checking the interoperability matrix (http://support.netapp.com/matrix). For Snap Creator 4.0 and vCenter 5 it reads: "The Snap Creator VMware plug-in is supported only on Windows. If the user is using a non-Windows Snap Creator server, they need a Snap Creator Windows agent to run the VMware plug-in."
Our agent was running on a linux VM. When I instead used a Snap Creator agent running on Windows the restore worked.