Why WWW.text == null ?

//Why t == null ?

import System.IO;

var t : String;

function Start(){

Get( t );

Debug.Log( t ); 
}

function Get ( txt : String ) {

var url : String = "http://www.redsky.org.cn/00test/works/001.txt" ;

var www:WWW = new WWW(url);

yield www;

txt = www.text;

Debug.Log( txt );

}

Cause you’re not setting t, your setting txt:

// Replace this:
txt = www.text;

// For this:
t = www.text;