Movieclip trouble!

i have a movieclip called main_mc. inside this movieclip i’ve included a dynamic textfield called txt1 and another movieclip called themv.

what im trying to do here is, when the user clicks anywhere on the main_mc, the string in txt1 will be converted into a movieclip instance name (txt1 will bare the string “themv”) and it will move the particular movieclip baring that instance name.

this is the code i have. but its throwing an error.

main_mc.addEventListener(MouseEvent.CLICK, gettxt);
function gettxt(event:MouseEvent):void
        main_mc.txt1.text = "themv";
	var myString:String;
	myString = main_mc.txt1.text;
	var myMV:MovieClip = this[myString];
	main_mc.myString.x = 0;
	main_mc.myString.y = 0;

And the error its throwing…
TypeError: Error #1010: A term is undefined and has no properties.
at Untitled_fla::MainTimeline/gettxt()