Advice sought on Timer switched power

I have a second chauffe eau that is, at least should be, switched by a timer in my fusepanel.
There is a rotary timer that switches when desired, and is connected to a Hager et321.
The Hager is a 3 phase switch, 3 live in, 3 feeds out. The timer switched live is connected to contact A1 on the Hager, A2 is connected to Neutral. At all times the Hager is buzzing, which does not seem right. It does not switch the supply on to the water heater either. I have seen conflicting wiring diagrams for these, one shows it with A1 as a live signal, a2 to neutral; the other shows a1 as a live signal, and a2 as an alternative live signal. The second one is understandable allowing the EDF heures creuse signal to feed a1 then a timer to a2.
Is anyone familiar with this and willing to advise?

Neutral goes to one of A1/2 and the switched live from the timer or meter goes to the other. You can’t connect two timer signals.

@ptf, thank you for a quick reply. That makes perfect sense and works fone, apart from a bit of buzzing from the et321 when it switches on by the signal. I see that Hager discontinued this specific device, I don’t know for what reason.
I had to be doubly careful because it is controlled by a differentiel that switches the polarity… Live in then comes out and is feed in to N on all the CBs afterwards. After a lot of testing and probing I have switched over the tails out of the differentiel to be correct. It makes no difference to the electrical devices, but I don’t like having items labelled ‘N’ having Live feed.