I beleive the database only stores data for 30 days (default setting) or you can change it to a maximum of 120 days.
Also make sure that CP reported is running and connected to your CP server.
From the Help file:
To confirm a first-time connection to a CallPilot server
Once you successfully log on to Reporter, click System Log.
Look for the message “Connection to CallPilot Server” in the log. If the message appears, your connection to CallPilot was successful.
If an error occurs, click Logout & Erase to delete the Reporter profile and try to log on again. If Reporter still cannot connect to CallPilot, ensure that the network connection between the stand-alone web server and CallPilot is working, and then try to log on again.
The message “Connection to CallPilot Server” only appears in the System Log the first time an administrator logs on to a CallPilot system. If there is a subsequent successful logon by another administrator, the message does not appear in that administrator's System Log.
You may also want to reboot the CP Reporter Web server if you haven't done so in awhile.