closeIcon always display

Hi,
My purpose:
1.If the tab is selected, it can be closed , and display the closeIcon
2.If the tab is deselected, it can not be closed , and do not display the closeIcon


isc.TabSet.create({
ID: "tabSet",
tabBarPosition: "top",
width: 400,
height: 200,
tabs: [
{title: "Blue", canClose: true,closeIcon:"pieces/48/pawn_blue.png"},
{title: "Green",canClose: true,closeIcon:"pieces/48/pawn_green.png"}
],
tabSelected : function ( tabNum, tabPane, ID, tab){

tabSet.setTabProperties(tab,{canClose:true})

},
tabDeselected : function ( tabNum, tabPane, ID, tab, newTab){
tabSet.setTabProperties(tab,{canClose:false})
}

});


Problem is, the closeIcon still display when tab is deselected

How can I do?
Thanks.