[news.eclipse.modeling.gmf] Ambiguous extensions error in generator mode

[pns57@xxxxxxxxxxx (Pev)]

Hi everybody,

I have a problem when I want to generate the "generator model" (.gmfgen).
In the last stage "specify Transformation options" I push the button 
"finish" and I have an error message: 
"Ambiguous extensions String variableNameStem(DecorationFigure fig) and 
String variableNameStem(Polyline fig) for param types"
I think it's a problem with the graphical model?

Can anybody help me?

Thank you in advance

Best regards

Pev