Questions about xml&flash gallery kirupa tutorial

Hi everyone, I’m new to this forum and a new flash user.
I hope not to posting in the wrong section…
In the last weeks I tried studying many tutorials concerning the creation of flash photo galleries with thumbnails controlled by xml file, just to create my own website to promote my 3D graphics works.
I completed succesfully the two tuts I found here but there’s a little problem with the alpha effect created for thumnails viewing: if you take a look at the end of [URL=“http://www.kirupa.com/developer/mx2004/thumbnails5.htm”]page5 you’ll understand what I mean.
I would like to invert the alpha effect made by kirupa on thumbs RollOver and RollOut, so to see the thumbs clearer on RollOver and darker on RollOut.
If I simply invert the two alpha values I get the desired result, but since I roll over the thumbs don’t become darker; I’d like to have a darker look at opening event.
It’s probably a very simple question but I’m still completely noob on flash and AS questions, so please be fair with me and sorry for my english.
Thanks in advance.