InvientChart, how to start

Hi, can someone explain me how to start with InvientChart add-on? I have do something like this :

  • Make a new Vaadin Project
  • Add the jar to WebContent/WEB-INF/lib
  • Add jquery.js and highchart.js to WebContent/js folder
  • Create a class that extend ApplicationServlet and add url to above js file
  • Change the servlet class in web.xml (see above link)
  • Make a InvientPie class
  • Run the project and compile the widgetset

I’m getting this error :

Failed to load the widgetset: /chartProject/VAADIN/widgetsets/com.example.chartProject.widgetset.ChartProjectWidgetset/com.example.chartProject.widgetset.ChartProjectWidgetset.nocache.js?1368453503030

Am I missing something? Can someone please tell me the right sequence to use this add-on clearly. Thanks