You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: Can you please help me to book a ticket from OAK to SFO?

ASSISTANT: May I know your desired travel dates please?

USER: My travelling dates are on Dec 19 and Dec 21.

ASSISTANT: Please wait a while.

USER: Sure.

ASSISTANT: Do you have any other requirement that you are looking for?

USER: I need a connecting flight.

ASSISTANT: May I know your name to proceed further?

USER: I am Debra Williams.

ASSISTANT: Do you have any other specifications?

USER: No.

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

USER: Ok, not a problem. Thank you.

ASSISTANT: Thank you for opting us.