What's wrong with the stadistics graph, beacause it show less players that conected; worst, it shows that there was over 2 player when there was already 26 at 15 o'clock.

The historical data graph does not show a "maximum" because that would be terribly inaccurate in showing the popularity of a server. The historical data graph shows averages over each hour. Please note the graph is in US Eastern Time and may be up to an hour behind, depending on when you refresh the page.