Graph doesn't start to zero (0)

Hello,

My analytics dashboard chart (y-axis) doesn’t start to zero. It starts at 8 or 10. On the google analytics website, the chart starts to 0.
I use wordpress multisites feature if it can help. I can’t check my others website because there is always traffic on them.

Thank you.

http://ww.wp.xz.cn/extend/plugins/google-analytics-dashboard/