title: MS SQL - LEAD is not a recognized built-in function
body: <p>I am using MS SQL server managment studio 2014, when trying to use the function 'LEAD' or 'LAG', I get an error saying it is not a recognized built-in function, even though when hovering over the function, it does show it as a built-in function.
  Everywhere I looked it says the function should be available from version 2012 and up, but I can't get it to work.
  Help will be greatly appreciated, thanks!
  <a href="http://i.stack.imgur.com/vnmVP.png" rel="nofollow">image of the message showing when hovering ove the function name</a></p>