Problem with ezcGraphBarChart and the setting of the Y-Axis

Hi,
right now, I'm stuck within ezcGraphBarChart and an interesting problem. As
you see at http://dev.nicohaase.de/graphTest.png, the Y-Axis does not start
at zero, but somewhere higher. Thus, the bars are too short: one is even not
visible!
You can see my code at http://dev.nicohaase.de/graphTest.phps which does
only set some basic things and the data. I derived my code from the
ezcGraph-tutorial at http://ezcomponents.org/docs/tutorials/Graph#axis, but
there must be some tiny setting about this I haven't found yet...
With best wishes from rainy Germany
Nico