I realized that there were no longer backups. Some changes in directories with the machine were necessary. Changed Backup directory to a mounted Network drive (same as it was before). Tried instant backup by menu. Some box appeared for 1 ca. sec and vanished can't see what's in there. The question in appearing box for "see directory" got a "yes", BUT NO NEW FILE THERE.
Another try to C:\temp (1PW is in C:), and in addition to another disk D:\temp within the workstation also to no avail.
I see the folder in Preferences>Backup the directory in menu is selectable but it is greyed out, thus not accepted?
Rights and Releases have been checked and found OK by an Netadministrator.
Thanks for advise how to clear that.