paging not working with ajax call to servlet

Code:

Ext.onReady(function ()
{
var itemsPerPage =5;
var store = Ext.create('Ext.data.Store',{
   storeId: 'resultsetstore',
   autoload: false,
   pageSize:itemsPerPage,
   fields:
           [
                {name: 'firstname', id:'firstname'},
                {name: 'email', id:'email'},
                {name: 'mobileno', id:'mobileno'}
           ],
           proxy:
                   {
                       type:'ajax',
                       enablePaging: true,
                       url:'./RetrieveRecords'
                   },
                   reader:{type:'json',totalProperty: 'total'}
});
store.load();


Ext.create('Ext.grid.Panel',{
    store:store,
    layout: 'border',
    height:300,
    renderTo: Ext.getBody(),
    columns:
            [
                    {
                        header: 'Email',
                        id: 'email',
                        dataIndex: 'email',
                        //autoSizeColumn : true,
                        flex: 1,
                        editor: {
                            xtype: 'textarea'
                        }
                    },
                    {
                        header: 'Action',
                        id: 'action',
                        align: 'center',
                        xtype: 'actioncolumn',
                        autoSizeColumn: true,
                        //flex: 1, 
                        sortable: false,
                        items:
                                [
                                    {
                                        icon: 'images/icons/cancel.png',
                                        tooltip: 'Delete',
                                        handler: function (grid, rowIndex, colIndex)
                                        {
                                            var rec = grid.getStore().getAt(rowIndex);
                                            var email = rec.get('email');
                                            Ext.Ajax.request(
                                                    {
                                                        url: './deleteRecords',
                                                        params: {email: email},
                                                        method: 'GET',
                                                        success: function (response)
                                                        {
                                                            Ext.Msg.alert("successfully deleted" + " " + response.status);
                                                            window.location.reload();
                                                        },
                                                        failure: function (response)
                                                        {
                                                            Ext.Msg.alert("failed" + response.status);
                                                        }
                                                    });
                                        }
                                    }
                                ]
                            }
                        ],
                dockedItems:
                        [
                            {
                                xtype: 'pagingtoolbar',
                                store: store,
                                dock: 'bottom',
                                displayInfo: true
                            }
                        ]
                    });
});

paging not working with ajax call to servlet