Just found that the manual "Update now" in Date & Time not work.
And if I selcet "Use NTP Server" nothing is updated in a certain interval in the GUI ? !
To get the a date and time I've always to select : SYSTEM --> Date & Time Then it changes BUT : The time is not correct ? ? ?
Differs about 4 min. to :http://www.timeanddate.com/worldclock/?query=berlin