Attribute View no 'Add Key Attribute'

Hi,

I don't know if this is just a beginner problem, but I tried to run some of the training data and fail to compile an Attribute View simply cause the Key Attribute is missing. I click on a field and I get entries like Add To Output, but that's it.

But to my understanding I would need this, or am I wrong?

roland

P.S.: Hana Studio 1.80.3