You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you today?

USER: I want to attend a Seminar in Seattle. Can you please help me for booking the flight ticket?

ASSISTANT: Sure, I am here to help you with that. Can I know your planned trip dates?

USER: My travelling dates are Aug 17 and Aug 19.

ASSISTANT: May I know your airfield locations?

USER: My airport codes are DTW and SEA.

ASSISTANT: Can I know your name?

USER: My name is Paul Allen.

ASSISTANT: Is there any other preference?

USER: I want to return on evening.

ASSISTANT: Ok, please wait for a while.

USER: Ok, I will wait.

ASSISTANT: We are regret to inform you that, there are no flights available based on your journey dates.

USER: Anyway, thanks for the information.

ASSISTANT: Thank you for consulting us.