Question about "adding thumbnails"

First of all, I want to appologise for some mistakes, I am Dutch normally, but I will try to explain in English.

I want to make a website where I can show some illustrations I made. So I neaded a scrollbar. I first found on Kirupa “Photo Gallery using XML in Flash”. Step by step I managed to make my own photo gallery. The next thing was to have thumbnails also, so I found this on Kirupa : “adding thumbnails”
It is made from the same man. I did everything the tutorial said, I copied the action-scripting… but I still don’t see my thumnails. In the preview, there isn’t even a warning that he doesn’t find the pictures…
Can anyone help me with this problem?

I am not very good in actionscripting.