You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Can you please book me a flight ticket from DCA to OAK to meet my family?

ASSISTANT: Sure, to book a ticket may I know your planned travel dates?

USER: I have planned to travel on Feb 17th and return on Feb 19th.

ASSISTANT: Do you have any other specifications?

USER: I like one connecting flight.

ASSISTANT: Kindly mention your name?

USER: Kevin Lee.

ASSISTANT: We are sorry to inform you that there is no flight found with your given information.

USER: Ok, no problem.

ASSISTANT: Thank you.

USER: Thank you.