using TicketWorkflowOpTriage never worked

[yokim@…]

I had followed wiki:AdvancedTicketWorkflowPlugin#Example to use TicketWorkflowOpTriage, but it doesn't work.

This is a part of my trac.ini:

type = new -> *
type.name = type distribution
type.operations = triage
type.triage_field = type
type.triage_split = bug -> bug_new, improvement -> improvement_new, question -> question_new

question_answer = question_new -> question_answer
question_answer.operations = set_owner
question_answer.permissions = TICKET_MODIFY

even though i selected the radio button of "type distribution", the step never go on. it still "new". i expect the trac should go to next step "question_answer".

the necessary option for useing TicketWorkflowOpTriage is already done.

what am i missing now?