jQuery selector not working in IE7-9

jQuery selector not working in IE7-9

Hi 

I have this simple code:
  1. var data = $('<xml><customtag>If you see this it worked!</customtag></xml>');
  2. alert(data.children('customtag').html() || "This time it failed");
Here is the jsfiddle:  http://jsfiddle.net/me2loveit2/bZwC9/

I can't figure out why this wont work in older IE versions.
I tried to call 
data.children() <-- without selector works in IE8
but 
data.children( 'customtag' ) <--Does not work for me in IE8

Thanks for any insights!