触发点击事件无效

Question

我试图触发section_1但它不起作用？我研究了它，因为我加载文件，我需要触发一个事件，但我很困惑。 section_1也没有添加该类。

我试过这个，但没有加载文件虽然jquery，这是有效的。我做错了什么？

$(function(){

    $(document).on('click','.popup_upload', function(){
        $('#upload').load('ajax/upload_contents.php');
    });

    // album, choose pic 
    $(document).on('click', '#add-album', function(){
        $('#album-pic').trigger('click');
    });
    // album change function
    $(document).on('change', '#album-pic', function(){
        if(this.files && this.files[0]){
            var reader = new FileReader();
            reader.onload = function(e){
                $('.placeholder_pic').attr('src', e.target.result);
            }
            reader.readAsDataURL(this.files[0]);
        }
    });

    var tracks_display = $('.uploaded-tracks');

    var number_of_tracks;

    var name;

    var origional_name;

    var file;

    var number_of_files;

    var section_1 = $('#add-cover-id');
    var section_2 = $('#add-tracks-id');
    var section_3 = $('#add-upload-id');


    $(document).on('click', '#validate_section_one', function(e){
        e.preventDefault();

        var album_name = $('#upload-name').val();
        var genre = $('#upload-genre').val();
        var price = $('#upload-price').val();
        var album_cover = $('#album-pic').val();
        var error = $('#panel2-1 .errorMsg');

        if(album_cover == ""){
            error.show().html('Choose a album cover!');
        } else if(album_name == ""){
            error.show().html('Give your album a name!');
        } else if(genre == "0"){
            error.show().html('Choose your album genre');
        } else if(price == "0"){
            error.show().html('Choose a price!');
        } else {

            section_1.addClass('disabled');
            section_2.removeClass('disabled');
            section_2.trigger('click');
        }

    });