Sold out tickets
You'll find all of the tickets that are available when you click the Tickets button on the event page. If there are no ' - ' or ' + ' buttons and it says as Sold out next to the ticket type, there are no more tickets available for that ticket type and Quicket cannot issue any more tickets.
Booked out tickets
If a ticket type reflects as Booked out, this means that some tickets are currently being purchased. It would be best to check the event page at a later time to see if those tickets have become available.
Tickets not on sale
You won't be able to select any tickets for an event if the sales period has ended or if the ticket sales have not yet started. If sales haven't started yet, you'll see the date that the tickets are meant to go on sale. If ticket sales have ended, Quicket cannot issue any more tickets.