misplaced points when all values are 0

[Martesan]

Hi, i found a little issue: if all data points are = 0 , the points are misplaced (top left corner instead of the center of the chart

you can take a look here: http://jsfiddle.net/Max_S/uEJh3/

if at least 1 point is !=0 then everything works.

Thank you!