function valida_comentario(form) {
    var error = "";
	if (form.nombre.value=="") {
	   error = "You must enter the Name\n"
	}
	if (form.email.value=="") {
	   error = error + "You must enter the E-mail\n";
	}
	if (form.comentario.value=="") {
	   error = error + "You must enter the Comment\n";
	}
    if (error!="") {
	  alert(error);
	  return false;
	}
  }