xtype：combo未触发expand事件

Question

我正在使用EXTJS 3.4版本并面临xtype: combo的问题。

对于某些记录，它会为某些记录扩展事件。

我的代码如下：

{
    xtype: 'combo',
    labelWidth: 0,
    store: this.comboBoxStore,
    mode: 'local',
    triggerAction: 'all',
    displayField: 'asupDate',
    minListWidth: 500,
    valueField: 'asupId',
    itemSelector: 'div.search-item',
    forceSelection: true,
    editable: false,
    width: 180,
    id: 'combo' + '-' + this.ptype + '-' + this.asupRecord.get('sysRefId'),
    listeners: {
        expand: function () {
            //stop special keys operations... like j, k and 1,2,3,4.
            this.getEl().addListener('keydown', me.onKeyDownFunction);
            //Call loadAsupRange to load/populate asupRange dropdown.
            var cdvMainPanelObj = Ext.ComponentMgr.get('cdvMainPanel');

            if (!Ext.isDefined(me.asupRecord)) {
                var seriallNo = me.systemRecord.get('sn');
                var systemNo = me.systemRecord.get('sysId');
            } else {
                var seriallNo = me.asupRecord.get('sysSerialNo');
                var systemNo = me.asupRecord.get('sysId');
            }
            cdvMainPanelObj.loadAsupRange(this, systemNo, seriallNo, me.ptype);
        },
        render: function () {
            Ext.QuickTips.register({
                target: this.id,
                text: utp_toolTips.cdv_dropdown_asupRangeCombo
            });
        }
    }
}

请让我知道我做错了什么。