I'm building a mac osx application with a nice graph in it made with Core-Plot. Its a line chart (scatterplot) with multiple points on it visualized with a plotsymbol circle.
My goal is to have a shown a label with the value of the point when a user mouse over a point in the chart.

I already have added NSTracking to the graph and this works but i'm lost in how to translate the plot point/plotsymbol to the coordinates so i know when it rollovers a point and show a label. 

Somebody has an idea?
Thank you all