Residual block in UIScrollBar HELP NEEDED!!

[Mokas]

I have personalized my UIScrollBar to look as I want it just editing the different components in the library.
Everything looks amazing but when there's no content to show in the scroll, instead having no scroll at all, I get this Fu%$&Ç square instead.
How can I delete this?
Everyone is pussing me to make it disappear!!!

EXAMPLE (http://www.costablancainside.com/question/)

The square appears exactly where scroll should be...

[Mokas]

What happens with this question?
The answer is so obvious that no one wants to answer or nobody knows the answer? Should be fine to know to stop waiting for the miracle to come !

[Mokas]

This is what I have found by myself in the Macromedia Support Center:

The square is a bug and the way to remove is as follows:

To place the following line of code at the beggining of the actionscript:

Object.registerClass("ComboDownArrowDisabled", MovieClip);

In my case, it doesn't works neither !