Does anyone know how to do this?

I have a simple AreaChart with several data points, some of the y values are
zero. Flex extends the y-axis to -0.25 by default in this scenario; in effect,
a double line is created--one at y=0 (lowest AreaChart data) and one at y=-0.25
(the y-axis minimum).

If I force the y-axis minimum to be zero in this case, only one line renders;
however, the line that renders is the axis line--not the chart line. The chart
line is rendered under the axis and only the top half of the data point shows.

Google has figured it out with their Analytics product, so I know it can be
done. Their y=0 points and lines both render on top of the x-axis. I'm just not
sure how.

I tried messing around with the chart's BlendMode property, in order to layer
the chart on top of the axis line; however, I couldn't get it to work. I don't
know if that's the property to modify.

Any help is appreciated. Thank you.