You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: I am Catherine Anderson and I want to book a flight ticket to Washington DC-DCA on 09/21 from Atlanta, GA-ATL to attend my niece first birthday.

ASSISTANT: Could you please send me your return date?

USER: I intend to return on 09/23.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Thanks for being waiting. Unfortunately, there are no flights found according to your details.

USER: Ok, thanks for your information.

ASSISTANT: Thank you for contacting us.