Radiator Heating - OpenStudio

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I am trying to model a building in OpenStudio. It's an old building and it uses Hot Water Radiators for its heating. I added a Hot-Water-Loop in the (HVAC Systems) tab. Then I added the equipment (Low Temp Const. Flow Radiant) in each thermal zone and linked them to the Hot-Water-Loop. Although, every time I try to run it, it gives me the following error:

* Severe * [Branch][Hot Water Loop Demand Branch 2][components][0] - Missing required property 'component_name'.

* Severe * [Branch][Hot Water Loop Demand Branch 2][components][0] - Missing required property 'component_object_type'.

I have tried doing the same on a different model and it gave the exact same error (they both even had the same "Branch 2" number in the error)

Does anyone have suggestions on how to model radiator-heating for a building? And do you know what is causing this error?

Thank you so much!