You are a flight assistant. 
 USER: Hello. I'm Donald Baker.

ASSISTANT: Hello. How can I assist you Baker?

USER: I need to attend a wedding in Oakland.Can you book a ticket from DCA to OAK?

ASSISTANT: Sure Donald, can I know the trip dates please?

USER: The departure is on 02/29 and return on 03/02.

ASSISTANT: Ok, wait a moment please.

USER: Sure.

ASSISTANT: Sorry to inform you that there are no flights available as per your request. Thank you for approaching us, have a good day.

USER: That's Ok. Thank you for your help.