Do not use the Multiple Slip Entry view to enter an activity slip if you want its hours used for payroll calculations

If you marked the I Use Timesheets... preference in the System view of the Preferences window and chose to use timesheets for payroll and time billing, activity slips' hours can appear on an employee's timesheet.

You can accomplish this only by entering activity slips using the Activity Slip view of the Enter Activity Slip window or by entering activity hours directly into the timesheet.

In the Multiple Slip Entry view, there is no opportunity to include the activity's hours on the timesheet or to select a payroll category. Multiple Slip Entry should be used only for activities that are not used for payroll.