i have download the sampel but it is only for polygon feature i have a point feature and it doesn't work
There are two parts in the sample:
1) showing how to display a chart inside a maptip : this part should not be impacted by the geometry type
2) using a chart symbol to display the states : can be tweaked to work with point features. It even simpler with point features since you don't need to create new graphics, you can symbolize your point features directly.
What kind of issue do you get?