This didn't work either:
SELECT
ID, ApplicationDate, Company, [Job Title], RejectionDate,
IIf(IsNull(RejectionDate), DateDiff("d",ApplicationDate,Date()),Null) AS TotalDays,
IIf(IsNull(RejectionDate), DateDiff("d",ApplicationDate,RejectionDate) AS TotalDaysComplete,
Date() AS EndDate
FROM...