InvientCharts not working

Hi guys, I am working with Vaadin 6 and want to use InvientCharts because it is free. After compiling the widgetset, all vaadins component instead of invientCharts are working. The image in the attachment shows the error…

After trying everything, including setting up a complete new project, I followed this tutorial:

But it is still not working and shows the same error. Has anyone an idea what is going on here?

Thanks in advance!