Custom GWT widget in GWT Dev mode

Hi

I have added a custom widget using the Vaadin Widget wizard, following the
Doing it the Simple Way
notes. When I compile the widgetset directly from Eclipse, no errors are reported - and the widget appears correctly. However, compiling through GWT Dev mode gives:

Widget class com.solstoneplus.campus.base.widgetset.client.ui.VMatrixChart was not found. The component com.solstoneplus.engagement.base.ui.component.MatrixChart will not be included in the widgetset.

I checked the
GWT Dev Mode
notes, but it seems that using the Vaadin wizard should have been enough. Is there something else I need to set up to make this widget compile through GWT Dev Mode?