Node Red: Relais on Smart Solar

Hello,

I would like to control a heating rod in Node Red. To do this, I would need to use the relays from two Smart Solar. Everything should actually fit in my Flow, but I can't switch the relays. Do I have to make a presetting in the devices themselves, as I have to do with the Cerbo (setting: Manual)?
Or is it because the Smart Solar are currently "Off" due to the lack of solar input?
Or what could be the reason that the relays do not switch?

Greetings from the Ambergauer

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