are you aware that there are 2 underscores in the 'ggs__#' declarations in the manifest but that the image element in your OP only has one underscore in it?
ie:
Code:
ggs_001.jpg vs.
ggs__001.jpg
seems like you might be typing single underscores into the html, double underscores in the opf, and the filenames themselves are with single underscores.
or based on your last post possibly the reverse?