Need help w/ script - Don't load the external SWF if it's already loaded

I’m pretty sure this is simple, but I can’t seem to figure it out.

Trying to figure out the actionscript so that if an external SWF is currently loaded and I click on it’s button in the navigation it doesn’t load the SWF again.

I tried modifying the code that’s in the <a href=“ - Transitions Between External SWFs”>Transistions Between External SWFs</a> but didn’t have any success

Thanks! Below is what’s currently on my button.

on (release) {
//load Movie Behavior
if(_parent.ad_container == Number(_parent.ad_container)){
} else {
//End Behavior