TypeError: Error #1009: Cannot access a property or method of a null object reference

Hi,

I have parent.swf which is load the a child.swf

I gave alreay gave few version of both swf to my clients. Now i am on the postion to update only the child.swf.

Now i want to add scroll panel on the child.swf.When i try to add that it shows error:

TypeError: Error #1009: Cannot access a property or method of a null object reference.

    at fl.containers::ScrollPane/setScrollDrag()

    at fl.containers::ScrollPane/draw()

    at fl.core::UIComponent/callLaterDispatcher()

    at flash.display::DisplayObjectContainer/addChild()

    at yume_survey_cs_as3_fla::MainTimeline/frame1()

The coding on child.swf is:

import fl.containers.ScrollPane;

var a:ScrollPane=new ScrollPane();

addChild(a);

with out any code change on parent.swf, i want to add this scrollPane on child which need to work fine with parent.How to do that?.

Thanks,

SIva