我究竟做错了什么？没有错误

function showComments(wallID){
    $.ajax({
      url: "misc/showComments.php",
             type: "POST",
      data: { mode: 'ajax', wallID: wallID }, 
      success: function(msg){

      var $msg = $('#showWallCommentsFor'+wallID).find('.userWallComment');
// if it already has a comment, fade it out, add the text, then toggle it back in
if ( $msg.text().length ) {
  $msg.fadeOut('fast', function(){
    $msg.text( msg ).slideToggle(300); 
  });
} else {
  // otherwise just hide it, add the text, and then  toggle it in
  $msg.hide().text( msg ).slideToggle(300); 
}
      }
    });
}
function showComments(wallID){
    $.ajax({