Shoutbox

I can get this script to work with pictures in my documents, but only with JPEGs - .tif files dont work at least.  Anyway, when i try to change the filepath, it gives me a toast saying that their are no pictures in the folder, but there blatantly are, cos if i copy the filepath from the options box into windows explorer, it gives me a nice folder full of JPEG pictures - far from the none as promised in the toast message.  Has anyone else got this script to work with a different filepath, or can anyone suggest why mine doesn't work, and give advice accordingly  (please bear in mind I don't really understand how scripts work - I just use them )
Thanks