AS3 Erreur, help needed!

stop();
btn_standard.addEventListener(MouseEvent.CLICK, standard);
function standard(evt:MouseEvent):void {
   gotoAndStop(1);
}
btn_metric.addEventListener(MouseEvent.CLICK, metric);
function metric(evt:MouseEvent):void {
   gotoAndStop(2);
}
 
var standardweight:Number=0;
 
//restrict to numbers and fullstops
txtpounds.restrict = "0-9, . ";
txtinches.restrict = "0-9, . ";
txtkg.restrict = "0-9, . ";
txtmetre.restrict = "0-9, . ";
 
submit_standard.addEventListener(MouseEvent.CLICK, stopUser);
 
function stopUser(evt:MouseEvent):void {
   if (txtpounds.text == "") {
      stage.focus = txtpounds;
   }
   else if (txtinches.text == "") {
      stage.focus = txtinches;
   }
   else {
      standardweight = Number(txtpounds.text)/((txtinches.text)*(txtinches.text));
         if (standardweight <= 18.5) {
            gotoAndStop(3);
         }
         else if(18.5 >= standardweight <= 24.9) {
            gotoAndStop(4);
         }
         else if(25 >= standardweight <= 29.9) {
            gotoAndStop(5);
         }
         else if(30 >= standardweight <= 34.9) {
            gotoAndStop(6);
         }
         else if(35 >= standardweight <= 39.9) {
            gotoAndStop(7);
         }
         else if(standardweight >= 40) {
            gotoAndStop(7);
         }
         else {
            gotoAndStop(1);
         }
   }
}