I saw some similar issues on google but those were all with updates and inserts. This is merely getting information, its basically saying that it doesn't find it.
I also read that someone noticed a bug and their solution was to change the order of where the column was found. What is the order/structure of your ost_ticket table?
Mine (working) is:
ticket_id
ticketID
dept_id
priority_id
staff_id
email
name
subject
topic
phone
phone_ext
ip_address
status
source
isoverdue
isanswered
duedate
reopened
closed
lastmessage
lastresponse
created
updated
It looks like all of our code is the same too, FWIW.