D'oh! We will investigate why this ticket code didn't work for you. In the mean time, please try a few things: Ensure that there are no leading or trailing spaces before or after the code, you should just use the 6 digits you were given. Also, if you recently switched browsers it may take a few minutes for the code to be able to be used again.
We've been having problems with ticket codes not working properly. Here is the advice we've received from Placement about how to use these codes: Do not enter your private access ticket code into the browser to test it. Please wait until you have your wallet/purse/credit card with you and are ready to complete the entire order before you begin the process. If you do get an error message about the ticket code being 'In use', please close your browser try again after 30 minutes, which is when the code session times out.