Urgent ! dwz rich client framework javasrcipt of linet chart problem

I draw a line chart , if the value of y is negative , it does not show up , only partially displayed on the screen y is a positive number , it should be how to do it . Like drawing, four quadrants can only see the first quadrant .
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this framework or do not use a lot of problems
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landlord if the words themselves will flex package a try, before drawing with are not used jfreechart you say that thing