Check for a null date in a formula field.

Check for a null date in a formula field.

In my application, I would like to create a custom field that would perform the following actions
 
      If (initial_date and clear_date are BOTH NOT null/empty) - display "Complete"
 
      else if (initial_date is NOT null/empty but clear_date IS empty) - display "Pending"
 
      else - display "Incomplete"
 
For some reason, even when I try to check if a date is NULL in a simple formula, nothing will show up e.g. if((initial_date ==null),"Test1","Test2")
 
Any help would be appreciated!