when i try to chose the widget “visits summary” and there the “preview” it shows me the info :
-> Evolution over the last days
Displaying Graphs in Piwik requires Flash >= 9.0.0. More information about displaying graphs in Piwik. <-
Flash 10 is installed on the computer and no blocking is choosen for the domain.
pie chart, bar chart, evolution graph are shown within the other widgets.