I'm having some issues getting the disclosure option to properly work.

I have three separate and individual panels each held in a carousel. The very last item in the carousel is a List, and I set up a simple dataStore to test out the functionality. However, while the list displays correctly (I can also click on list items to highlight them), I can't get the disclosure option of the List to work. Here's my code:

Code:
Ext.regModel('Notebook',{
            fields: ['phenotype','amino_acid']
        });
        
        demoNoteStore = new Ext.data.Store({
            model: 'Notebook',
            sorters: 'phenotype',
            getGroupString: function(record){
                return record.get('phenotype')[0];
            },
            data: [
            {phenotype: 'A', amino_acid: 'test'},
            {phenotype: 'J', amino_acid: 'TEST'},
            {phenotype: 'K',  amino_acid: 'TESTTEST'}
            ]
        });
        
        
        
        var ugc_Panel = new Ext.Panel({
            html: "Site of the future UGC Table Panel"
        });
        var notebook_Panel = new Ext.List({
            store: demoNoteStore,
            tpl: '<tpl for="."><div class="phenotypes"><strong>{phenotype}:</strong>{amino_acid}</div></tpl>',
            itemSelector: 'div.phenotypes',
            singleSelect: true,
            grouped: true,
            disclosure: {
                handler: function(){
                    alert('work!');
                }
            },
            //indexBar: true,            
        });

var labCarousel = new Ext.Carousel({
            //fullscreen: true,
            indicator: false,
            height: 250,
            width: 500,
            items: [gizmoPanel, ugc_Panel, notebook_Panel],
            activeItem: 0
        }).show();
Thanks for any help anyone can provide!

EDIT: Turns out our dev environment was still using 0.9.1. Upgraded and it works fine.