You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER: Margaret Lopez here. Can you please help me in booking a flight ticket from IAD to DFW?

ASSISTANT: Sure, on what dates are you planning to travel?

USER: I would like to travel on Aug 14 and return on Aug 16.

ASSISTANT: Do you need a stop over?

USER: Yes, I need connecting flight.

ASSISTANT: Ok, please wait.

USER: Sure.

ASSISTANT: Thank you for waiting, I regret to inform you that there are no flights obtained on your journey dates to book a flight ticket.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for choosing us.