I found a solution, please help me to understand if this can lead to other problems.
In `function zipAddSubalbum($base, $offset, $subalbum)` I replaced line 22:
`$new_offset = $offset.$subalbum.'/';`
with
`
if ($offset != "" AND strpos($base, $offset)) {
$new_offset = $subalbum.'/';
} else {
$new_offset = $offset.$subalbum.'/';
}
`
This seems to work, but I tested it only for my own case, as described above...