Attempt to create Azure AD Application programmatically failing

Attempting Applying permissions programmatically as per https://docs.microsoft.com/en-us/power-bi/developer/register-app. I have created the AD Application, and assigned the permissions required. I really want to automate consent.

I have successfully created the application, and the service principal. In posting to https://graph.microsoft.com/beta/OAuth2PermissionGrants with body:

{
    "principalId":  "<from AD user obtained via Get-AzureRMADUser>",
    "clientId":  "<service principal id from above created service principal>",
    "resourceId":  "c78b2585-1df6-41de-95f7-dc5aeb7dc98e",
    "consentType":  "Principal",
    "expiryTime":  "2019-12-12T22:04:37Z",
    "startTime":  "2017-12-12T22:04:37Z",
    "scope":  "Dataset.ReadWrite.All Dashboard.Read.All Report.Read.All Group.Read Group.Read.All Content.Create Metadata.View_Any Dataset.Read.All Data.Alter_Any"
}

I am getting the following error:

{
  "error": {
    "code": "Request_ResourceNotFound",
    "message": "Resource 'c78b2585-1df6-41de-95f7-dc5aeb7dc98e' does not exist or one of its queried reference-property objects are not present.",
    "innerError": {
      "request-id": "55f8836a-ec3c-4581-8122-82352b2411c1",
      "date": "2017-12-12T22:04:35"
    }
  }
}