The following classes could not be instantiated: - net.kenyang.piechart.PieChart (Open Class, Show Error Log)

[MarialenaShiamma]

I added the library in my project, but when I tried to put in layout the pieChart, i had this 'error' message in the graphical layout: "The following classes could not be instantiated:

• net.kenyang.piechart.PieChart (Open Class, Show Error Log)". The project is compiled without any errors, it just doesn't show the pie chart.