Connect lines with empty values.

<applet code=com.objectplanet.chart.BarChartApplet
 archive=chart.jar width=300 height=200>
<param name=seriesCount value=2>
<param name=sampleValues_0 value="65,43,54,65,76,87,69,87,98,90,98,90,80,98,79,87,98,79,87,60">
<param name=sampleValues_1 value="55,x,x,x,x,x,x,x,x,x,x,,80,x,x,x,x,x,x,x,60">
<param name=connectedLinesOn value=true>
<param name=range value=100>
<param name=lowerRange value=40>
</applet>