Cant add resource group through Powershell

Cant add resource group through Powershell

I have tried Invoke-RestMethod and Invoke-WebRequest using the three kinds of data in the pictures. Nothing works. Its either complaining about "EXTRA_PARAM_FOUND" or "Invalid data in the input". What am I doing wrong?

I tried executing using these commands
Invoke-RestMethod -Method Post -Uri $RestURL -Headers $RestHeaders -Body $Data1
Invoke-WebRequest -Method Post -Uri $RestURL -Body $Data1

I have tried without headers and with and without content-type. No change.