We are using the latest version of Akeeba Ticket System and noticed a "bug". This happens on Joomla! 2.5.11, using the developer release, on PHP 5.3.18.
When you open a ticket, and click the "Assign To" dropdown, the list does not appear and you can't assign the ticket. Assigning the ticket from the Tickets Overview works just fine.
On a side note, your "Mandatory Information" text isn't added to the editor when someone clicks the green button to confirm that he / she wants to submit a ticket anyway...