i have created a window, on the toolbar i have added a button,menu and combobox, when i open window for first time menu,button and comboBox are visible but when i open the window for IInd time combobox is not visible.

------------code-------------
var detailViewData = new Ext.data.Store({
proxy: new Ext.data.HttpProxy({
url:'analyzerSummaryHandler.do?cmd=GetViewData&screen=DETAIL SCREEN&viewName='+currentViewName+'&companyId='+companyId
}),
reader: new Ext.data.JsonReader({
root: 'viewData',
totalProperty: 'rCnt',
id: 'id',
fields: [{name: 'valueColum'},{name: 'lableColum'}]
})
});

var selectDetailViewButton = new Ext.form.ComboBox({ //combobox
loadingText: 'Getting Views...',
//typeAhead: true,
triggerAction: 'all',
lazyRender:true,
mode: 'remote',
store: detailViewData,
//width: 150,
emptyText: 'Change View',
valueField: 'valueColum',
displayField: 'lableColum'
});
---window----
analyzerDrilDownWin = new Ext.Window({ //window
title : 'Detailed Grid',
maximizable : true,
resizable : true,
layout : 'fit',
height : 400,
width : 1000,
html :html_t,
closeAction : 'destroy',
tbar:new Ext.Toolbar({
id:'detailToolbar',
items:[

new Ext.Toolbar.Button({text:'Export Details',
tooltip:'Export Grid Data To Excel File',
cls:"x-btn-text-icon",
icon:'resources/images/excel.png',
handler:AnalysisDetailExportHandler}),
new Ext.Toolbar.Separator(),
//detailSelectView,
{
text:'Change View',
//iconCls:'bmenu',
menu: selectViewDetailMenu
},
new Ext.Toolbar.Separator(),
selectDetailViewButton
]
}),
items : [detailGrid]
});
plz do reply...