Thank you, Nancy
No, I don't have any other extensions. This is what I have:
I did the installation like explained in the tutorial "Installing the jQuery Slider Dreamweaver Extension" and everything worked, until the final message "Die Menüs konnten nicht installiert werden ..."
And of course I tried also to close and restart Dreamweaver and besides my computer - no change.
Before I contacted you, I tried other things you explained in similar cases - without success .
I am really interested to buy this software, but before, I would like to try, how it works.
MS