A small reminder of the file format & size you have to use:
One the Touch: PNG files, 600x800. Grayscale if possible, but color works too (you can even play with an alpha channel if you like).
One the PaperWhite: PNG files, 758x1024. Grayscale if possible, but color works too (you can even play with an alpha channel if you like).
You NEED to follow these directives: non-PNG files will be discarded by the
hack, and broken files or files in the wrong resolution will confuse the framework and trigger weird issues.