Hide Div depending on screen res

Can anyone see whats wrong with this Jquery, I found it around the web somewhere but i cant get it working :

<script> 
$(document).ready(function() {

if ((screen.width>1024)) {

$(".advert").css('display', 'block'); 
}
elseif ((screen.width<=1024))  {

$(".advert").css('display', 'none'); 
}
});
</script>

Code (markup):

Basically the idea is to show an advert ( inside a div called advert ) but for it only to display on screen resolutions above 1025px wide. I dont want to use CSS3 to do it because its not compatible with older IE browesers so Jquery seems the best option with some people blocking Javascript too.

Any idea's ?

 

Anyone ?.....

 

you missing part of the script that set $(document).ready(function() with any data...