The software does not compute the number of weeks worked.  You must set a Preference in order to track Weeks.  At the AMS Payroll Menu, select Payer>Payer Edit>Preferences > Check Entry Fields, Preference 7. Need Weeks Worked and click OK.  When entering checks, enter the desired number on the Weeks line of the AddChk screen.  If you are importing from some other system be sure that this system also tracks Weeks so that the number can be imported.