solution for div bg swap

[johnnyblotter]

Hi folks

I need to solve the problem that can be seen in the attachments. When a nav item is hovered, the area below needs to have a dark transparent bg image. Because I need IE support for the pngs I set it up as follows...there is an empty div below the nav set to the appropriate dimensions. Not semantic I know but that's the only way I can get the bg pngs to swap in and out. So anyway, I need to figure a way where when any nav item is hovered over, the bg will switch on the empty div. I am using this jquery statement which isn't working:

$function() {
$("nav a").hover(over,out);
	function over (event) {
     $(.spacer-bg-off).css("background", "url(images/spacer-content-bg.png)");
   }
   function out (event) {
     $(.spacer-bg-off).css("background", "none");
   });

Can someone take a look at these images and see if you have any ideas? I am stuck on this one...thank you...