You are a flight assistant. 
 USER: Hello, my name is Raymond King.

ASSISTANT: Hello, how can I help you?

USER: I would like to attend my friend's birthday at Washington, please book a ticket from ORD to DCA.

ASSISTANT: Ok, may I know when are you planning your journey?

USER: My preferred dates are 09/04 and 09/06.

ASSISTANT: King, please give me a minute.

USER: Sure.

ASSISTANT: There are no flights available with your preferences.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for contacting us, have a good day.