Add reply url through Graph API

Hi all,

I have an application in Azure AD that has permissions to Windows Azure Active Directory application. My goal is to create a new reply url to another application in Azure AD with the first application's clientid/secret. I am able to get a list of all applications but when I update the Application with a new replyurl it throws an exception:

 app.ReplyUrls.Add(String.Format("http://{0}.blabla.com/", newsubDomain));
 await app.UpdateAsync();

Exception:

Authorization_RequestDenied

Insufficient privileges to complete the operation.

The app that does the update has all the permissions needed. Am I missing something or is it just not possible?

thanks