Unloading XML before loading another

This image gallery I am working on loads the thumbnails(from the XML) into a scrollbar. It works for the first one fine, but when I click on another button for another gallery it adds the thumbs of the new gallery at the end of the ones already there, but what I trying to do is have the previous thumbs unload then load the new xml with the appropriate thumbnails.

I have tried removeNode(); to unloadMovie(); and various other functions but nothing works. The XML does not unload before the next one loads EVER. The removeNode(); doesnt even remove all the children, which i thought it was supposed to.

xmlData.firstChild.removeNode();

This is in a function called on the release of all buttons, but it doesnt do anything. This function is located in the same frame as the loadXML function. Is this the wrong place to put it?

Any thoughts or discussions are very appreciated.
Thanks.
Peace.