Issue with Binding data to chart control using wcf

Hello all,

How to bind data to chart control using Wcf service reference ?

I am trying to bind data to chart by using e.result;

chartname.itemsource=e.result;

or

((barseries)mychart.series[0].itemssource=e.result;
I m getting an error "Object reference is not set to instance of an object"

please suggest me a way to solve this issue.