Seems like you are following the same approach I would: try every combination. When you tried it with a photo, was it roughly the same size (both in pixel count and in file size)? I’m wondering if their machine has some sort of file size limit.
Just to be clear, on the machine that is having problems, the file does not even show up as an option to load, correct? Or can you select the file and it does not work?
If the file is not showing up, try a really basic file name (e.g. A.JPG) with no spaces or mixed case. I doubt this is the problem, but you never know. Also, try shrinking the file to different sizes (both pixel count and file size) to see when/if the machine starts recognizing them.
Pauley