SAC Conditional Formatting not usable on calculated column in table

Hi,

I have thresholds defined in the model on invidual account members. I however also want to apply thresholds on a calculated column - see the column below (ACT - BU). On the right of the screenshot you can also view the screenshot that should be defined for the column. However, the option is greyed out in the story. Has anyone experience with this to make it a selectable option?

Thank you in advance