"Count" is not working in Form Calculation Widget

I am looking to have the form calculation widget "count" the number of courses registered for. I have gotten this to work in other forms but it is not working in this particular form. It always says 0. Can you help me? Thank you!

The count() function will only work for Radio Button or CheckBox fields. It won't work for Dropdown field. You may consider changing the current dropdown field to Checkbox to do this.