Image ordering in "Album contents"

to maintain sequence in step-by-step instructions, my users name their pictures 001.jpg 002.jpg 003.jpg... and then mass upload the bzipped file. Images are correctly inserted in alphabetical order in album display, however when one goes into "Album contents" the alphabetical order is not maintained (namely: 001, 004, 005, 008, 007, ...), which makes difficult to add text for step-by-step instructions.