Multisim wave window does not show

First time i had started the vwf simulation named "majority_vote" of the book from B.Dueck 2 edition in Quartus II Web v.4.0 it worked great, even after I had changed the wires as a test followed by a second successful simulation.

But now I never get any good simulation and the Y output fails to show any result. I only managed to run the Inputs a,b and c right as a group in a binary value count. And any next retry only results in an completely empty Wave diagram.

What do I have to reset or save correctly to end this problem? I even tried it over and over again by starting with the majority_vote.bdf file without success.