function checkform ( form )
{
  // see http://www.thesitewizard.com/archive/validation.shtml
  // for an explanation of this script and how to use it on your
  // own website

  // ** START **
  if (form.randomNo.value == "") {
    alert( "Please enter the 4 digit code." );
    form.randomNo.focus();
    return false ;
  }

  if (form.name.value == "") {
    alert( "Please enter your name." );
    form.name.focus();
    return false ;
  }

  if (form.email.value == "") {
    alert( "Please enter a valid email address." );
    form.email.focus();
    return false ;
  }

  if (form.message.value == "") {
    alert( "Please give us your message." );
    form.message.focus();
    return false ;
  }

// ** END **
  return true ;
}