This menu saves the weaving metamodel model into an ".ecore" file.
This is not a transformation model (in ATL), thus the "extraction into
ATL" action will fail.
Actually, the "Class2Relational-Trace.amw" is the trace generated by the
already modified transformation, "Class2Relational-WithWTracer.atl". The
generation of the trace is generated by the last action (transformation)
of the example.
You need to execute the "ATL2WTracer.atl" transformation first. This
transformation generates a "Class2Relational-WithWTracer.ecore", which is
a transformation model. This is the model that should be extracted into
ATL. The extracted ATL is used to generate the AMW trace model.