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

Answer 1

You're accessing imagesCollection variable in line 41, but haven't initialized it - it still contains null

Either change

[Bindable]
public  var  imagesCollection:ArrayCollection;

To

[Bindable]
public  var  imagesCollection:ArrayCollection = new ArrayCollection();

or add

imagesCollection  = new ArrayCollection();

to the beginning of xmlService_resultHandler method.