Icon setting for ComboBox is not working

Hi all,

I have a ComboBox 'oStatus', and add ListItem like this:

var oItem = new sap.ui.core.ListItem({
text:'Error',
icon:sap.ui.core.IconPool.getIconUIR('status-error'),
key:sStatusName
});
oStatus.addItem(oItem);

The icon is not shown on ComboBox. but I set icon to a Button, setting icon is worked:

var oButton = new sap.ui.commons.Button({icon : sap.ui.core.IconPool.getIconURI("status-error")});