function CheckCValues()
{
  var retvalue=true;
  if(document.coupon.prefix.value.length <4)
    {
       alert('The prefix of the CODE is incorrect');
       document.coupon.prefix.focus();
       retvalue=false;
    }
  if(retvalue && document.coupon.pin.value.length <7)
    {
      alert('The second part of the CODE is incorrect');
      document.coupon.pin.focus();
      retvalue=false;
    }
  
  if (retvalue==true) { 
      document.coupon.submit(); 
   }
}