ADOBE ANIMTE variable spacing in text field

Hi, 

I am using the following code to set the font size according to my textfield length. I was trying to do the same with letter-spacing but with no luck. Any suggestions?

 input.text = "12121212121212jkjkjkjkj12";
	   
	   
	   trace(input.length);
	  
if (input.text.length <= 22)
	
{
	   
      del.htmlText = '<font size="40">' + input.text + '</font>';
	
}

if (input.length > 22)
	
{
	   
      del.htmlText = '<font size="22">' + input.text + '</font>' ;
	
}