Ensure the Selection Criteria fields are blank. This will ensure all employees that you approve time for are visible.
Change the "View By" to 'All Time Before'. If you expect the employee to have previously entered time, they should appear here. If the time is future dated, you can look for 'All Time After' a particular date.
To ensure that you are looking at all employees in your group, you can review them at this path:
Manager Self-Service > Time Management > Report Time > Timesheet.
