# Problem adding List component

**URL:** <https://forum.kirupa.com/t/problem-adding-list-component/278757>\
**Category:** Uncategorized\
**Created:** [January 5, 2009, 11:57am UTC](https://forum.kirupa.com/t/problem-adding-list-component/278757 "2009-01-05T11:57:38Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![eldersoares](https://avatars.discourse-cdn.com/v4/letter/e/94ad74/32.png) [@eldersoares](https://forum.kirupa.com/u/eldersoares)\
**Post date:** [January 5, 2009, 11:57am UTC](https://forum.kirupa.com/t/problem-adding-list-component/278757/1 "2009-01-05T11:57:38Z")

</div>

Hi!  
I created a class that adds a list component in a certain moment. Something like this:

```auto
import fl.controls.*; 
...
var myList: List = new List();
...
addChild(myList)

```

but in the last line, i get a huge error. I realized the error message disappears and everything works well if i put the list component in the library. Is it really necessary??? Here’s the error message. Thank you all in advance 😉

```auto
TypeError: Error #1009: No se puede acceder a una propiedad o a un método de una referencia a un objeto nulo.
    at fl.containers::BaseScrollPane/drawBackground()
    at fl.controls::List/draw()
    at fl.core::UIComponent/callLaterDispatcher()
TypeError: Error #2007: El valor del parámetro child debe ser distinto de null.
    at flash.display::DisplayObjectContainer/addChildAt()
    at fl.controls::BaseButton/drawBackground()
    at fl.controls::BaseButton/draw()
    at fl.core::UIComponent/drawNow()
    at fl.controls::ScrollBar/draw()
    at fl.core::UIComponent/callLaterDispatcher()
TypeError: Error #2007: El valor del parámetro child debe ser distinto de null.
    at flash.display::DisplayObjectContainer/addChildAt()
    at fl.controls::BaseButton/drawBackground()
    at fl.controls::BaseButton/draw()
    at fl.core::UIComponent/callLaterDispatcher()
TypeError: Error #2007: El valor del parámetro child debe ser distinto de null.
    at flash.display::DisplayObjectContainer/addChildAt()
    at fl.controls::BaseButton/drawBackground()
    at fl.controls::LabelButton/draw()
    at fl.core::UIComponent/callLaterDispatcher()
TypeError: Error #2007: El valor del parámetro child debe ser distinto de null.
    at flash.display::DisplayObjectContainer/addChildAt()
    at fl.controls::BaseButton/drawBackground()
    at fl.controls::BaseButton/draw()
    at fl.core::UIComponent/callLaterDispatcher()
TypeError: Error #2007: El valor del parámetro child debe ser distinto de null.
    at flash.display::DisplayObjectContainer/addChildAt()
    at fl.controls::BaseButton/drawBackground()
    at fl.controls::BaseButton/draw()
    at fl.core::UIComponent/callLaterDispatcher()
TypeError: Error #2007: El valor del parámetro child debe ser distinto de null.
    at flash.display::DisplayObjectContainer/addChildAt()
    at fl.controls::BaseButton/drawBackground()
    at fl.controls::BaseButton/draw()
    at fl.core::UIComponent/drawNow()
    at fl.controls::ScrollBar/draw()
    at fl.core::UIComponent/callLaterDispatcher()
TypeError: Error #2007: El valor del parámetro child debe ser distinto de null.
    at flash.display::DisplayObjectContainer/addChildAt()
    at fl.controls::BaseButton/drawBackground()
    at fl.controls::BaseButton/draw()
    at fl.core::UIComponent/callLaterDispatcher()
TypeError: Error #2007: El valor del parámetro child debe ser distinto de null.
    at flash.display::DisplayObjectContainer/addChildAt()
    at fl.controls::BaseButton/drawBackground()
    at fl.controls::LabelButton/draw()
    at fl.core::UIComponent/callLaterDispatcher()
TypeError: Error #2007: El valor del parámetro child debe ser distinto de null.
    at flash.display::DisplayObjectContainer/addChildAt()
    at fl.controls::BaseButton/drawBackground()
    at fl.controls::BaseButton/draw()
    at fl.core::UIComponent/callLaterDispatcher()
TypeError: Error #2007: El valor del parámetro child debe ser distinto de null.
    at flash.display::DisplayObjectContainer/addChildAt()
    at fl.controls::BaseButton/drawBackground()
    at fl.controls::BaseButton/draw()
    at fl.core::UIComponent/callLaterDispatcher()

```