Missing Date Entries - Calendar Overview

I am using Outlook 2003 Calendar. I put in all my work days and that way I
keep track of bookings and payments.
When there is an appointment on a day the date goes Black Bold in the months
overview, I then know I worked that day.
For some reason in the overview I cannot see days I worked on before Feb
2007 yet if I click on a day there are entires.

Anyone have any thoughts or can help me please.
Thank you
Simon