Dashboard Prompts for Derived Fields

Summary

Attempting to use a derived field as a dashboard prompt

Content

Hi All, 

I created a derived "Region" field based on our company field. I would like to be able to add this derived field to the dashboard prompt so the end user can filter through the results by region. Unfortunately, I don't see it in the 'add column prompt' or anywhere else. Any help would be appreciated! I am sure it is something simple I'm missing. 

Thanks, 

Todd