Problems configuring geoext tree

Question

I am facing some difficulties configuring properly my geoext tree. I'll appreciate if anybody can help me.

When I try to open the "images" folder, the node stays rounding, trying to load something forever.

Here is my code:

var DNI2008_dec = new OpenLayers.Layer.WMS("2008_DNI_dec",
        "http://localhost:8080/geoserver/wms", {
            layers: "personal:2008_DNI_dec",
            transparent: true,
            format: format,
            tiled: true,
            tilesOrigin : map.maxExtent.left + ',' + map.maxExtent.bottom
        }, {
            buffer: 0,
            displayOutsideMaxExtent: true,
            ratio: 1,
            opacity: 1,
            visibility: false
        }
    );

map.addLayers([DNI2008_dec]);

    var LayerTree = new Ext.tree.TreePanel({
    title: 'Map Layers',
    renderTo: 'layers',
    loader: new Ext.tree.TreeLoader({
                    applyLoader: false
                }),
    root: {
        nodeType: "async",
        text: "Layers",
        leaf: false,
        expanded: true,
        children: [
            new Ext.tree.TreeNode({
                nodeType: "folder",
                text: "images",
                leaf: false,
                children: [
                       new GeoExt.tree.LayerNode({
                           text: "test",
                           nodetype: "gx_layer",
                           layerStore: mapPanel.layers,
                           layer: "2008_DNI_dec",
                           leaf: true
                       })
                ]
            })
        ]
    }
});