flex - Actionscript error cannot import library -

in below action script file error saying cannot import mx.controls.label,how resolved

  package {     import flash.display.sprite;     import mx.controls.label;      public class cld extends sprite     {         public function cld()         {             var mylabel:label = new label();             mylabel.text = "hello";             addchild(mylabel);         }      }  } 

make sure flex project , in project properties->flex build path->library path import framework.