Text instead of thumbnails plupload

Question

I have text (JPG, PNG, etc.) ( https://i.stack.imgur.com/gVCag.png )instead of thumbnails plupload jQuery. How can i repair this? I want thumbs, any idea? It's my code:

$( document ).ready(function() {
    $("#uploader").plupload({
        runtimes : 'html5,flash,silverlight,html4',
        url : "upload.php",
        max_file_size : '5mb',
        chunk_size: '1mb',
        resize : {
            width : 2000,
            height : 2000,
            quality : 90,
            crop: false,
            preserve_headers: false
        },
        filters : [
            {title : "Zdjęcia", extensions : "jpg,gif,png"},
            {title : "Archiwa Zip", extensions : "zip,avi"}
        ],
        rename: true,
        sortable: true,
        dragdrop: true,
        views: {
            list: true,
            thumbs: true, // Show thumbs
            active: 'thumbs'
        },
        flash_swf_url : '../js/Moxie.swf',
        silverlight_xap_url : '../js/Moxie.xap'
    });
});