Why isn't my ExtJS GridPanel paying attention to the limit parameter?

Question

I have a JsonStore:

var store = new Ext.data.JsonStore({
        root: 'Data.items',
        remoteSort: false,
        fields: ['ClockTime', 'EmpId'],
        proxy: new Ext.data.HttpProxy({
            url: AppRootPath + 'Something/GetSomething',
            method: 'POST'
        })//proxy
});//new Ext.data.JsonStore

I then call Load on this store with the following:

store.load({params:{start: 0, limit: 25}});

I have a grid to display this data in:

    var grid = new Ext.grid.GridPanel({
    store: store,
    title:'Employees',
    stateful: true,
    id: 'grid',
    stripeRows: true,
    stateId: 'excp_list',
    bbar: new Ext.PagingToolbar({
        store: store,       
        displayInfo: true,
        prependButtons: true,
        emptyMsg: "No records to display",
        pageSize: 25
    }),
    viewConfig: {
        forceFit: true
    },
    columns: [
        {header: "Emp Id", width: 40, dataIndex: 'EmpId', sortable: true},
        {header: "Clock Time", width: 40, dataIndex: 'ClockTime', sortable: true}
    ]
 });

I expected this to only display 25 records/rows per page. however it only displays one page with the total 160 records on this page. Am I missing something obvious here?