Calling Function inside an iFrame

Calling Function inside an iFrame

Hey guys,
 
How do you call a function inside an iFrame using jQuery?
 
function MyFunction() {
      alert("Test");
}
 
Javascript - works
var f = window.frames.myIFrame;
f.MyFunction(); //works
 
jQuery - fails
var $f = $("#myIFrame");
$f.MyFunction();  //fails
$f.contents().MyFunction(); //fails
 
Thanks!!