Extjs ค่าที่เลือกจาก Checkbox ไม่ออกมา วานแนะนำทีครับ

/*!
 * Ext JS Library 4.0
 * Copyright(c) 2006-2011 Sencha Inc.
 * [email protected]
 * http://www.sencha.com/license
 */

Ext.define('User', {
     extend: 'Ext.data.Model',
     fields: [
         {name: 'name', type: 'string'},
         {name: 'price',  type: 'float'}
     ]
 });

 var myStore = Ext.create('Ext.data.Store', {
     model: 'User',
     proxy: {
         type: 'ajax',
         url: 'php/newgrid.php',
         reader: {
             type: 'json',
             root: 'users'
         },
         extraParams: {
            mytype: 'list'
        },
         actionMethods: {
            create: 'POST', read: 'POST', update: 'POST', destroy: 'POST'
    	}
     },
     autoLoad: true
 });
 
 var myCheckbox = Ext.create('Ext.selection.CheckboxModel', {
    listeners: {
        selectionchange: function(sm, selections) {
            //Ext.getCmp('grid-win') -- อ้างอิง id
            Ext.getCmp('grid-newGrid').down('#removeButton').setDisabled(selections.length === 0);
        }
    }
});
 

Ext.define('MyDesktop.NewGrid', {
    extend: 'Ext.ux.desktop.Module',

    requires: [
        'Ext.data.ArrayStore',
        'Ext.util.Format',
        'Ext.grid.Panel',
        'Ext.grid.RowNumberer',
        'Ext.selection.CheckboxModel'
    ],

    id:'grid-newGrid',

    init : function(){
        this.launcher = {
            text: 'New Grid TEST',
            iconCls:'icon-grid'
        };
    },
    
    createWindow : function(){
        var desktop = this.app.getDesktop();
        var win = desktop.getWindow('grid-newGrid');
        if(!win){
            
            win = desktop.createWindow({
                id: 'grid-newGrid',
                title:'TESTING GRID WINDOW',
                width:740,
                height:480,
                iconCls: 'icon-grid',
                animCollapse:false,
                constrainHeader:true,
                layout: 'fit',
                items: [
                    {
                        border: false,
                        xtype: 'grid',
                        store: myStore,                   
                        selModel: myCheckbox,
                        columns: [
                        new Ext.grid.RowNumberer(),
                            {
                                text: "Company",
                                flex: 1,
                                sortable: true,
                                dataIndex: 'name'
                            },
                            {
                                text: "Price",
                                width: 70,
                                sortable: true,
                                renderer: Ext.util.Format.usMoney,
                                dataIndex: 'price'
                            }
                        ]
                    }
                ],
                dockedItems: [{
                        xtype: 'toolbar',
                        dock: 'bottom',
                        ui: 'footer',
                        layout: {
                            pack: 'center'
                        },
                        items: [{
                            minWidth: 80,
                            text: 'Save'
                        },{
                            minWidth: 80,
                            text: 'Cancel'
                        }]
                    }, {
                        xtype: 'toolbar',
                        items: [{
                            text:'Add Something',
                            tooltip:'Add a new row',
                            iconCls:'add'
                        }, '-', {
                            text:'Options',
                            tooltip:'Set options',
                            iconCls:'option'
                        },'-',{
                            itemId: 'removeButton',
                            text:'Remove Something',
                            tooltip:'Remove the selected item',
                            iconCls:'remove',
                            disabled: true,
                            handler: function(){
                                var TEST = Ext.getCmp('grid-newGrid').getView().getSelectionModel().getSelection();
                                console.log(TEST);
                            }
                        }]
                    }]
                        });
                    }
                    return win;
                }
});