Flash ComboBox Loading Error

[bimal]

I have a function that attaches a clip with a flash combo box component. Depending on user interaction this function gets called at various times.

function test()
{
var clip_with_combo_box_called_choice_mc:MovieClip = attachMovie(....);
clip_with_combo_box_called_choice_mc.choice_mc.onL oad = function()
{
this.setStyle("fontFamily", "_sans");
this.setStyle("fontColor", "0x333333");
this.setStyle("fontSize", 11);
this.setStyle("themeColor", "haloOrange");
}
}

In some cases the combo box loads fine and the styles are set as expected. But in some cases, the combo box fails to set the styles as per its onLoad function and when clicked the drop down list appears on the top-left corner of the canvas as opposed to below the combo box.

Please let me know if you guys have ever faced a similar problem. All suggestions to troubleshoot are welcome.
Thanks.