the solution was:
at the job configuration i had to change some settings.
here is what i did:
in the general tab: select Full – Using modified time you can not use archive bit in Linux…
in the Advanced tab: in the open file backup when advanced open file option is not used: select Never.
in the Linux, Unix, and Macintosh tab: select:preserve change time and Follow local mount points
BTW: Follow local mount points was responsible for empty folders :-(