Widgetset doesn't compile correctly

Hello,

I have a problem with a widgetset. I got a working widgetset from a former co-worker. I added just 3 classes to the widgetset. I made a .jar file with ant and put it onto our server. I’m using the Liferay Vaadin addon to compile the widgetset.
Now I get this warning:
[WARN]
Widget class de.mosgrid.chemdoodle.widget.client.ui.VSketcherCanvas was not found. The component de.mosgrid.chemdoodle.widget.SketcherCanvas will not be included in the widgetset.
[WARN]
Widget class de.mosgrid.chemdoodle.widget.client.ui.VMoleculeCanvas was not found. The component de.mosgrid.chemdoodle.widget.MoleculeCanvas will not be included in the widgetset.

When I open the .jar file both classes are in my sourcefolder. Do I need to specify in my web.xml or Widgetset.gwt.xml that this two components shout be in the widget?

If you need more details let me know.

Thanks in advance