Using midframe script

i followed Kirupa’s tut on transitions b/w external movies. I have everyhting working fine except one thing… The target movieclip is called “window” on the _root and it loads external swfs. i have download.swf loading into “window” and in download.swf (which has 3 buttons), i have another target movieclip (“empty”)loading other external swf’s into download.swf (hopefully that makes sense). One i click on the buttons in download, it will load the desired swf’s but i cant click on them for the second time, only once. here is the script that i have for those buttons (in download.swf) -

_root.window.btn_video.onRelease = function() {
	if (this.currMovie == undefined) {
		this.currMovie = "evideos";
		empty.loadMovie("evideos.swf");
	} else if (this.currMovie != "evideos") {
		if (empty._currentframe>=empty.midframe) {
			this.currMovie = "evideos";
			empty.loadMovie("evideos.swf");
			this.empty.play();
		}
	}
}

im not sure where im going wrong… anyone have any ideas?
thanks
tracy