Thank you so much, it worked at sudden.
I did not change anything in my code. I just created a new ressource and tried my "add" button again: worked at sudden.
What I like most "now - now"
"TvPlanItFrame.neuesEvent(now,now,'test',1); "
If somebody does not know the background, he will not understand my joy about "now-now" giving reasonable results. The first now is the start, the second now is the end of the event. If this is accepted, this means, I have not to mess around in "creating" an artificial end-date, in the case, I just have a start date, what is the rule, not the exception.
Now I am going to implement the smarter solution
" if datastore.Resources.Count > 0 then...."