If you are trying to run a report using data from the Attendee Table and it doesn't seem to be pulling all of the records, try this:
In SAMS, Open the Attendee Screen.
Sort by ID. You can do this by highlighting the ID Field Header in the List Tab.
Go to the top of the list by clicking the button.
If you see any ID numbers that look suspicious or "funny" (i.e. there is a minus sign in the number or any other out of place characters), delete them. This is a corrupted record.
Refresh your report and run it again.
All of your data should pull correctly.