im trying to use paging with data in client side (memoryproxy), but it doenst work.
all data are aways shown in grid and nothing happens when i try to change the page.
whats wrong??

Code:
 Ext.onReady(function() {
            Ext.QuickTips.init();

            store = new Ext.data.Store({
                totalProperty: 2,
                fields: [
                    {name: 'nome' },
                    {name: 'sexo' },
                    {name: 'nascimento',  type: 'date', dateFormat: 'Y-m-d h:i:s' },
                ],
                data: json_data,
                proxy:
                    {
                    type:'memory',
                    reader:{
                        type:'json'
                    }
                }

            });

            // create the Grid
            grid = new Ext.grid.GridPanel({
                store: store,
                columnLines: true,
                totalProperty:2,
                columns: [
                    {
                        text     : 'Nome',
                        flex     : 4,
                        width    : 200,
                        sortable : true,
                        dataIndex: 'nome'
                    },
                    {
                        text     : 'Sexo',
                        flex     : 1,
                        width    : 10,
                        sortable : true,
                        dataIndex: 'sexo'
                    },
                    {
                        text     : 'Nascimento',
                        width    : 135,
                        flex     : 1,
                        sortable : true,
                        renderer : Ext.util.Format.dateRenderer('d/m/Y'), // formato de exibição
                        dataIndex: 'nascimento'
                    }
                ],
                bbar: new Ext.PagingToolbar({
                   store:store,
                   pageSize:2
                }),
                height: 350,
                width: '100%',
                renderTo: 'grid'
            });
            grid.render();
            store.load({params: {start:0,limit:2}});
        });