IF statement gives blank cells

I have a table (Employee List) which has an employee ID, employee type and grade column. The following IF statement works, however some employees do not have a rank (blank cell instead) which means this formula brings back blank cells for them. How can I get this to bring back NONE for non-employees and employees with a blank cell as their rank, thanks.

IIf([Employee List].[Employer Type]="Employee",([Employee List].[Rank]),"NONE") AS Grade