Signal probe??

This is what the Altera guys say in "QUARTUS ii vERSION 7.2 Handbook Volume 3: Verification", page 1-8 (October 2007).

Your node might not appear in the simulation waveform and

might be ignored during simulation. This happens because the

node has been renamed or synthesized away by the Quartus II

software. To prevent this from happening, Altera recommends

using the register and pin nodes to simulate your design

So how are we supposed to simulate conbinational signals?? I think a good solution should exist.