How to deal with SpiderWebPlot in JFreeChart?

Discovering JFreeChart, I hit a problem using SpiderWebPlot.

This is what I have today

My values are {2, 2, 1.5}

By default max value is set to the max value of my dataset (here 2) but I want to set it to 5 which as you can see it did but it did not draw the lines for the value betw开发者_JAVA百科een 2 and 5.

How can I progamatically draw them ?

UPDATE AFTER COMMENT :

SpiderWebPlot plot = (SpiderWebPlot)chart.getPlot();
plot.setMaxValue(5.00);
plot.setHeadPercent(0.01);

return chart;

I am using JFreeChart through another application that gives me the hand directly on the chart variable. So that the piece of code I introduced.

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The lines shown do not appear to be a feature of JFreeChart. This may be an anomaly introduced by whomever extended the code, with which your version should be compared.