You are a flight assistant. 
 USER: Hello. I'm James Phillips.

ASSISTANT: Hello. How can I help you today?

USER: I want to meet my friend in Austin.Can you book a ticket from DCA to AUS?

ASSISTANT: Sure, may I know your preferable travel dates?

USER: The departure is on 07/14 and return is on 07/16.

ASSISTANT: Please allow me a moment to check for the availability of flight. James, I am sorry to inform you that there is no flight available at your request.

USER: Sure. That's really sad. Anyways, thank you for your help.

ASSISTANT: You are welcome. Thank you for contacting us.