Trouble Using DataProvider in External Class

Question

Hello,
I am creating a Flash form which will include a drop-down selection menu from which a user may choose their state. I originally accomplished this by adding a ComboBox to the stage and then populated the ComboBox's DataProvider object with an XML listing of all the state names and the corresponding values. Everything works as expected.
I have decided, however, that it would make the most sense to create an external class to accomplish the same thing. I have attempted to create such a class using the following code:
package {
import fl.data.DataProvider;
import fl.controls.ComboBox;
public class StateSelectionList extends ComboBox {
private var xml:XML;
private var dp:DataProvider;
private var cb:ComboBox;
public function StateSelectionList() {
xml = <states>
<state name="AL - ALABAMA" value="AL" />
<state name="AK - ALASKA" value="AK" />
<state name="AZ - ARIZONA" value="AZ" />
</states>;
dp = new DataProvider(xml);
cb = new ComboBox();
cb.dataProvider = dp;
cb.labelField = "name";
I then attempted to use this class in my Flash file by adding a ComboBox component to my library and then by creating a new StateSelectionList object and adding it the stage using the following code:
var states:StateSelectionList = new StateSelectionList();
addChild(states);
The data provider for the new object is empty, however, as one can find by tracing the length of the object's dataProvider property;
trace(states.dataProvider.length);
I am new to creating external class files so I am not sure why the new object is not populated with any data. Thanks in advance for any suggestions.
P.S. Please feel free to download the complete XML file I created for the states. The file includes all US states and possessions, US military states, and Canadian provinces and territories. http://windhorsemedia.com/private/states.xml

Answer 1

There is a something tricky:
first if you extend the combo box ther is no need to create a new instance in its constructor only to pass the data provider. This will work
    var xml:XML =<states>
            <state name="AL - ALABAMA" value="AL" />
            <state name="AK - ALASKA" value="AK" />
            <state name="AZ - ARIZONA" value='AZ' />
            </states>;
            dataProvider=new DataProvider(xml);
dataProvider is public from base class ComboBox so you can access it anytime. But the properties that are inspactable may be setted with effect only after second frame is passed so try this
public class StateSelectionList extends ComboBox {
        public function StateSelectionList():void
          addEventListener( Event>ENTER_FRAME, onsecondFrame, false, 0, true )
private function onsecondFrame( evnt : Event ): void
removeEventListener( Event>ENTER_FRAME, onsecondFrame
            var xml:XML =<states>
            <state name="AL - ALABAMA" value="AL" />
            <state name="AK - ALASKA" value="AK" />
            <state name="AZ - ARIZONA" value='AZ' />
            </states>;
            dataProvider=new DataProvider(xml);
            labelField="name";
Note, In my custom components when I extend the UIComponent a set the parameter in afterComponentParameters or CreateUI( I think this was the name ) methods but more fast is just to pass one frame and set the parameturs