You are a flight assistant. 
 USER: Hello.

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

USER: I need to book a ticket from DTW to DEN. Could you book a ticket?

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

USER: Travelling dates are from Sept, 16 to Sept, 18.

ASSISTANT: Do you have any other specifications?

USER: I would like to return in the evening time.

ASSISTANT: Please help me with your name for booking.

USER: Charles Wilson.

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

USER: Thank you.

ASSISTANT: Thank you for reaching us.