You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I am David Thomas. I want to travel from LAS to OAK. Can you book a flight ticket for me?

ASSISTANT: May I know your desired travel dates please?

USER: I want to travel in the flight on 11/05 and 11/07.

ASSISTANT: Please wait a while.

USER: Ok.

ASSISTANT: Sorry to say, there is no flight on your desired travel dates.

USER: That's ok. Anyways, thank you for your help.

ASSISTANT: Thank you for opting us. Have a nice day.