Selectin time range does not change graph

Hello,

when I select a week the graph shows multiple month. See the time range in this screen shot which is one week but the graph shows another range:

What I want is selecting a time range (often from monday to sunday) and the graph shall

  1. show only that range
  2. show visitors on a daily basis

What is wrong here?
How can I solve it?

Cheers,

Mike