Matsui DVD225 - JPEG problem?

I recently purchased a Matsui DVD225. I am very happy with it in most respects, except that it is supposed to run a photo slideshow from a JPEG CD, but it doesn't work when I tried, just says No Valid disk (I think).
The JPEG images open fine on my PC.

My question is - has anyone else successfully viewed JPEGs on their Matsui DVD225?
And if so, do all the JPEG's have to be copied directly onto the root of the CD, or can they be organised into separate folders?

I organised my JPEG files into separate folders on the CD because the basic manual shows a screenshot which seems to show folder navigation.