Bug in Adobe Flash ? The code doesn't work if I add a symbol

Hi,

Here's my code :

  import flash.text.TextField;
qtte_t1.addEventListener(Event.CHANGE,changeHandler);
qtte_t2.addEventListener(Event.CHANGE,changeHandler);
qtte_t3.addEventListener(Event.CHANGE,changeHandler);
qtte_t4.addEventListener(Event.CHANGE,changeHandler);
qtte_t5.addEventListener(Event.CHANGE,changeHandler);
qtte_t16.addEventListener(Event.CHANGE,changeHandler);

  function changeHandler(event:Event):void
  {
  calculatePayCheck();
  }
  function calculatePayCheck():void{
  var tome1:Number = 0;
  var tome2:Number = 0;
  var tome3:Number = 0;
  var tome4:Number = 0;
  var tome5:Number = 0;
  var tome16:Number = 0;


  var global:Number = 0;

  tome1 = Number(qtte_t1.text);
  tome2 = Number(qtte_t2.text);
  tome3 = Number(qtte_t3.text);
  tome4 = Number(qtte_t4.text);
  tome5 = Number(qtte_t5.text);
  tome16 = Number(qtte_t16.text);
  tome17 = Number(qtte_t17.text);
  tome18 = Number(qtte_t18.text);
  tome19 = Number(qtte_t19.text);
  tome20 = Number(qtte_t20.text);
  tome21 = Number(qtte_t21.text);
  tome22 = Number(qtte_t22.text);
  tome23 = Number(qtte_t23.text);
  tome24 = Number(qtte_t24.text);
  global = Number(prix_global.text);


  prix_t1.text = String(Math.round(tome1*1200));
  prix_t2.text = String(Math.round(tome2*1200));
  prix_t3.text = String(Math.round(tome3*1200));
  prix_t4.text = String(Math.round(tome4*1200));
  prix_t5.text = String(Math.round(tome5*1200));
  prix_t16.text = String(Math.round(tome16*1200));
  prix_global.text = String(Math.round((tome1+tome2+tome3+tome4+tome5+tome16)*1200));
  }

Everything is working great, but if I add a symbol on stage the calculs are completly buggy ! (no error message but I can't add the number I want and the calculs are wrong)

Do you know why ?

I can't add a form, a symbol, NOTHING. just bitmap. If I'm adding something, the sums are wrong.

Thank you,

steph