Problems setting variable from query string in flash

I’m creating a banner for a client that pulls in images via XML (sub_banner.xml.php) and depending upon which section of the site the user is in, PHP writes a query string sent via flashvars to set which section images to pull in.

The URL for example, after the query string is set for ‘conferences’ section of the site will be: [COLOR=DarkOrange]sub_banner.xml.php?headerImages=conferences[/COLOR]

All the PHP is in place, I’m just having trouble setting the query string (headerImages) in flash. I’ve tried: var headerImages:String = headerImages;

My background is HTML/CSS based and still learning AS2 so any help is much appreciated!