Need a little help concerning preloading external swf's

programming flash
1

I have a problem when loading external swf files. The preloader itself works just fine, bar extends as the loading proceeds and disappears when page is loaded, and so on.
However, as I click on one of my buttons the page starts play while it’s still loading, and I don’t want that. I want it to start at first frame only if fully loaded. How do I do that?

Ty for help.

My preloader code:

var mcLoader:MovieClipLoader = new MovieClipLoader();
var preload:Object = new Object();
mcLoader.addListener(preload);

preload.onLoadStart = function (targetMC) {
extLoader_mc._visible = true;
}

preload.onLoadProgress = function(targetMC,bytesLoaded,bytesTotal) {

var pctLoaded = Math.round(bytesLoaded/bytesTotal*100);
extLoader_mc.loaderBar_mc._xscale = pctLoaded;
extLoader_mc.pctLoaded_txt.text = pctLoaded +" %";

}
preload.onLoadComplete = function (targetMC) {
extLoader_mc._visible = false;
}

mcLoader.loadClip(“home.swf”,loader_mc);