Javascript that works in V2 doesn't work in V3

Hi,

I have a form that some fields are validate with JavaScript.  I attach the form:

The Javascript that works in V2 is: 

<script type="text/javascript">
function formbuilderCustomValidation() {
   var containError = false;
   var slct1 = document.getElementsByName('campoAprobacion')[0];
   var slct2 = document.getElementsByName('campoAceptarFactura')[0];
   var slct3 = document.getElementsByName('campoTipoAprobacion')[0];
   var txt1 = document.getElementsByName('campoOcultoTarea')[0];

   if(txt1.value != 'Radicar Factura VASA'){
      if(slct2.value.length == '')

      if(slct2.value == 'si'){
         if(slct1.value.length == '') 

         else{
            if(slct1.value == 'si'){
               if(slct3.value == '' || slct3.value == '0')

            }
         }
      }
   }
   
   return containError;
}
</script>

When I migrate the code into a CustomHTML, it doesn´t work.  I apply some flags to see the behavior but I can´t see the alerts.

Somebody can help me?

Thanks!!!