How to inlcude all records in a report, with a formula result of 0 or >0?

I'm reporting on classes scheduled for a certain location, and calculating the number of available seats per class. A formula will give me the net seats available (Max seats-count of students). BUT if there are no students enrolled, class does not appear on the report. Formula is {SCHEDULES.qy_sch_max} - Count ({WAITING_LISTS.no_emp}, {SCHEDULES.cd_crs)

What am I missing? Currently using Crystal 8.5 and reporting against a SQL database.

Appreciate your help.

christi