TSN evaluation Kit(RapID-TSNEK V0001)

when  i connect to one tsn port of this board, i can only receive many pdelay-req messages ,when i response this messages with related pdelay-resp and pdelay-followup later i can receive some sync and follow_up messages a short period of time,but soon  i can only see some  pdelay-req messages again . i want to know why there is no announce  Messages are  seen throughout the whole process but only many pdelay-reqs and a little sync / follow_up messages and how can i acquire announce messages from this tsn board. Looking forward to your reply,thanks!