XML scrolling gallery -- tutorial "Adding Thumbnails"

This tutorial was posted on June 14 05 but I seem to be having some problems with it. I get to the point of going through all the Action Script in the tutorial but I am then looking to run the script (export the Movie). Every time I do this, with my own coding or not, I see to the the same Error:
Error finding URL “file:/directory/directory/…/undefined”

this undefined error has reared its head before and it does seem to cause problems!

Could anyone give me some pointers on how to avoid this!

thanks,

Duck