When you say that you recently installed this as an upgrade to your existing system, what were you using before?
From the WIKI:
From time to time it will be necessary to upgrade your osTicket installation to the latest version, either to fix bugs or gain new features. Starting with version 1.6, osTicket is a complete rewrite with new database schema and code base making it hard to simply upgrade from previous versions.
Only previous versions from version 1.6 RC1 can be upgraded to the current version.
If your osTicket version is older than 1.6, you need to look into migration instead.
Our objectives is to make upgrading from an earlier release as painless as possible going forward and support migration from "discontinued" versions. we are working with osTicket community on the best way to upgrade or/and import data from previous versions including 3rd party helpdesk systems.
source: http://osticket.com/wiki/Upgrade_and_Migration(http://osticket.com/wiki/Upgrade_and_Migration)
It goes on to say that you should look at the forums for more up to date topics about migrating:
http://osticket.com/forums/forumdisplay.php?f=7(http://osticket.com/forums/forumdisplay.php?f=7)
If you cannot find it in there, then either no one has done it publicly or no one has done it.