Thanks Sylvain for your answer.
Im not working in an ATL environnement really - well, Im not sure about what does it mean. I did some school work with ATL, and I so have the perspective in Eclipse available with the magic Register button.
I need to check manually some programmatically generated instances. I<m working on an instance generator. ATL perspective offers me to register the metamodels, but I dont do anything with ATL.
It also sounds like the EMF geration doesn<t work properly as it doesnt generate anything...