You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I am Richard Gonzalez. Please book a connecting flight from IAD to IAH.

ASSISTANT: Sure, may I know your depart and return dates?

USER: I will start on July, 27 and return on July, 29.

ASSISTANT: May I know your depart time?

USER: My depart time is evening.

ASSISTANT: Do you have any other requirements?

USER: No.

ASSISTANT: Sorry, there are no flights found with your given details.

USER: It's ok, thank you for checking.

ASSISTANT: Thank you for opting us.