Xml slideshow/banner thingy

Hi all,

I’m making a flash banner, similar to one you can find on the Dutch webshop www.bol.com, offcourse with my own design.

For future maintenance, I made this banner with XML, so the texts and backgroundpictures all come out of the XML and all of this works fine. The ony thing that I can’t seem to work out is the way that the pictures fade in/out to each other. The scene had a white background and when a next picture come into view, the white background appears.
What I would like to do is to make the previous and next picture fade into eachother, without showing the white background.

The pictures load into a movieclip (imgholder), so I tried to use a simple alpha tween on the movieclip, from alpha=40 to alpha=100, but the white background appears anyway.

Anyone here who could point me into the right direction?

Thanks in advance.