You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. May I know your good name, Please?

USER: I am Ryan Parker. I want to book a flight ticket to meet my cousin in Las Vegas. Could you help me in flight booking?

ASSISTANT: Sure. May I know your source and destination airport codes, Please?

USER: Sure, my source from DC - DCA and my destination is DC - DCA.

ASSISTANT: May I know your travel dates, Please?

USER: My travelling dates from 04/10 to 04/12.

ASSISTANT: OK. I am very sorry to inform you that, There are no flights available for your travel dates. Thank you, For approaching us for ticket booking.

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

ASSISTANT: Have a great day.