Jquery html() not working more then once

Question

I am new in jquery. when i choose league 1 or 2 once, html() works but twice, not working. is there a solution or alternative about this error. I dont know where the problem is.

$("#league").on('change', function() {
  var leagueid = $(this).val();
  //alert(leagueid);
  if (lig > 0) {
    $.ajax({
      url: 'include/ajax.php?query=fixture',
      type: 'POST',
      data: {
        lid: leagueid,
        sid: <?php echo $curs_id; ?>
      },
      success: function(result) {
        //alert(result);
        if (result == 0) {
          $("#alert").html('');
          //$("#dates").slideDown();
          FetchTeams(leagueid);
        } else {
          $("#dates").slideUp();
          $("#alert").delay(600).queue(function() { 
            $(this).html("Fixture already exists!"); 
          }).fadeIn(100);
          $("#teams").html('');
        }
      }
    });
  } else {
    $("#dates").slideUp();
    $("#alert").html('');
  }
});