You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: Can you please help me in booking my flight ticket from IAH to IAD?

ASSISTANT: Yes, can you tell me your dates of travel?

USER: My travelling dates are from 06/15 to 06/17.

ASSISTANT: Do you have any preferences?

USER: Yes, I need a single connecting flight.

ASSISTANT: Give me a moment.

USER:  Also, my return time will be in the evening. Sure.

ASSISTANT: Sorry to inform you that there are no flights found on your requested criteria.

USER: It's ok, thank you for your help.

ASSISTANT: Can I know your name?

USER: Myself Matthew Lopez.

ASSISTANT: Thank you for reaching us.

USER: Most welcome.