You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I be at your service today?

USER: Please help me to book a flight ticket from IAD to SFO.

ASSISTANT: Sure, I will help you in booking the ticket. May I know your travelling dates please?

USER: My travel dates are 02 to 04 of Sep.

ASSISTANT: Do you have any other specifications?

USER: I need a connecting flight.

ASSISTANT: Please help me with your name for booking.

USER: I am Karen Johnson.

ASSISTANT: Sorry for this inconvenience, I could not find any flight with your requirements.

USER: Oh! that very sad to hear, thank you.

ASSISTANT: Most welcome.