Hello Dave,
thank you for taking the time to look at my problem. The date seems to be wrong because in the Notes database month and day are interchanged (Nov. 04.11. 2014 instead of Apr. 11.04.2014). The german date format is dd.MM.YYYY HH:mm
The specification says I should use yyyy-MM-ddTHH:mm:ssZ and so I did. I will do some further tests with a more simple form and will check if a Domino server on Windows behaves differently.
Henning