You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER: I would like to meet my brother at Dallas, will you help me in booking the flight ticket from IAD to DFW?

ASSISTANT: Sure, let me know your travel dates please?

USER: My preferable journey dates are Sept 11 and Sept 13.

ASSISTANT: May I know your connection limit?

USER: I need a flight with single connection.

ASSISTANT: Do you need any other preference?

USER: I prefer to travel in  business class which departs in evening time.

ASSISTANT: Can I know your name please?

USER: Myself Timothy Young.

ASSISTANT: Sorry to inform you that there are no flight services available on your given dates.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thanks for contacting us.