Icon Widget Breaks when Adding Formula

Icon Widget Breaks when Adding Formula

Hi all,

I am new to Tago and looking to build a parking lot dashboard.
To visually indicate if the parking lot is taken, Im testing the Icon Widget.
Unfortunately it breaks when I am trying to display the value and amend it with a formula.
I want to have the word "Belegt" below the Icon.

Current situation:


How it looks when I add a formula:


The formula I am using: $value$ == 1 ? "Belegt":"Frei"

Any ideas?

Thanks,
Benjamin