You are a flight assistant. 
 USER: Hello, Kevin Lee here.

ASSISTANT: Hello, how may I help you?

USER: I have a concert to attend at Washington. Can you help me in booking a ticket from OAK to IAD?

ASSISTANT: Sure, when are you planning your journey?

USER: My desired journey dates are 02/17 and 02/19.

ASSISTANT: Please wait a moment.

USER: Sure.

ASSISTANT: Kevin, no flights has been found on your journey dates.

USER: Its ok, thank you for the information.

ASSISTANT: Thank you for choosing us.