Trying to implement a filer for a ListSelect using a TextField

I am trying to implement a filter for ListSelect similar to what is available in Select. (I cannot use Select since i need multiple items displayed at the same time unlike Select)

ListSelect fullListW = new ListSelect();

Item aItem = fullListW.addItem(); // i have a custom object here as the argument in real code
fullListW.setItemCaption(aItem, “Test 1”);

Item bItem = fullListW.addItem();
fullListW.setItemCaption(bItem, “Test 2”);

I added a TextField next to the ListSelect and added this code

	TextField allFilter = new TextField();
	allFilter.addListener(new TextChangeListener() {
	    SimpleStringFilter filter = null;

	    public void textChange(TextChangeEvent event) {
	        Filterable f = (Filterable)
	        // Remove old filter
	        if (filter != null)
	        filter = new SimpleStringFilter("IID", event.getText(),
	                                        true, false);

When i enter filter criteria into the textfield the ListSelect does not display any values at all… I think the ‘IID’ property is where the problem is… but dont know what property to refer… tried printing the properties in the ContainerDataSource for the ListSelect and there was none in there…

What am i missing here…