W8.1 System Image Scheduled Task over Homegroup Network

Hello,

I have a home network of Windows 8.1 Pro 32bit and 64bit, and Windows 10 64 bit PCs. All 5 PCs are in the same Homegroup. I am wanting to set up a scheduled task to have weekly system image backups on all PCs saved to the one W8.1 64bit PC that has several TB of storage space. I only want each specific PC to be able to access its own backup share, so I have set sharing for "Specific People", not "Everyone".

I have created a scheduled task using Powershell.exe with the following commands:

wbAdmin start backup -backupTarget:\\DAVESPC\Fatman -include:C: -allCritical -user:Mike -password:Mink_819bc

Now this works just fine, but powershell opens and asks "Do you want to start the backup operation? Yes [Y] No [N]" I am required to make an input. If I type Y the process executes and my backup is saved over the homegroup to my PC with plenty of storage. I want to enable the scheduled task to run in the background without any human input.

If I add "-quiet" to the end of the line of code above, the backup fails to execute. I have set the Scheduled Task to have elevated privileges, and the user on the PC that runs the task is administrator.

I am completely new to using scheduled tasks and powershell.exe, so I am hoping someone with experience can tell me where I am going wrong. I thought adding -quiet to the end of the code would just make the process require no user input and be invisible, but it obviously does more.