This ticket is closed. You cannot add new messages
Ticket reply panel shows tickets.view.reply.closedNotice when the ticket is closed.
Why this happens
UI notice matching the API This ticket is closed. state — send is disabled.
Diagnose and fix
1. Do not retry reply on this ticket.
2. Open Create ticket with a new subject/context.
3. Reference the old ticket id in the new message if helpful.
4. See Tickets (member).