Anyone know how to get the SP2 keyboard to work with my new SP4 pro. I know its not the right size but in the past I could switch it to the SP3 with no issues. Is there a driver for it or anything? Every time I plug it in the back light lights up for a couple of seconds then goes off and the keyboard is totally unresponsive. I know the keyboard works because I am using it on my SP2 Pro now and it works fine. Any suggestions?