Conbee II -> SMaBiT Siren

I am building my alarm system on the Alarmo plugin which is working fine. Then I am trying to add an outdoor siren, which is thr SMaBiT AC2010/29A Siren

I’ve added the Siren as “light” in Phoscon. It works fine. But when adding the siren as an action for when the alarm activates, but it only comes with a very descrite “bip”. It feels like it just turns on and off instantly.

Any thoughts on how to make this work?