Ok, I'm fed up of searching, apparently this subject is not frequently talked about!

Basically, I have a text box in a flash, and the user can write a music file, or music URL in it, so the flash can play that music file from that location.

When the user clicks the play button, flash takes the text in the input box, turns it into a string, and uses that string, for the location / name of the file it needs to play.

For some reason, it isnt working.
I've tried many different combinations, but to no avail. And just when I thought I had strings and variables down.

Here is the code, the code i have so far, I will comment it as best I can.

Code:
//Start button is pressed.
function startoption(evt:MouseEvent):void {

// Next, flash is meant to create a string out of the text in the input box.
	var music_string:String = music_url.text;

// Then flash uses this string to play the song.
	var s:Sound = new Sound(new URLRequest(music_string)); 

	s.play(0, 5);
}
This doesn't work at all. It works when I specify the string, but not when the variable comes form the Input box. There must be something stupidly obvious I'm missing, can anyone help me out?