Need an RDP connection to a remote PC. I've downloaded the Microsoft Remote Desktop app, but when I try to use it to open the RDP file I get the message "The RDP file is not valid. Notify your network administrator." and then immediately after pressing ok, "The URL is not valid. Notify your network administrator." I know the RDP file works as I've used it on PCs, but can't get it to work on my Mac. Any advice?