The DuVoice integrates with the Legend/Magix extremely well, and I doubt it's the source of your problem.

Dial *00 (star zero zero) from an intercom or System Access button. All the LEDs and LCD elements should light up.

I've got one other thing to try, but I want to prove that the MWL actually works first.

"Press play and record at the same time" -- Tim Alberstein