As Cherie indicates, this could be due to changes in your database (imports/deletes).
Another possibility: It may be that you have the demo database open:
In the upper left hand corner of the Sage ACT! Window, it will have the name of the database (ex: "Sage ACT! - 'databasename'"). If it says 'ACT*Demo', you will need to open your production database. Click File > look at the bottom of the menu for the recently opened databases > click on your database.