You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, How can I help you?

USER: Could you please book a flight ticket from ORD to OAK?

ASSISTANT: Sure, May I know the travelling dates?

USER: I want to travel on Dec 11 and return on Dec 13.

ASSISTANT: Do you have any connection limit?

USER: I need a connecting flight.

ASSISTANT: Is there any other requirements?

USER: I want to depart in the evening.

ASSISTANT: May I know your name?

USER: My name is Frank Johnson.

ASSISTANT: Please wait a minute.

USER: Sure.

ASSISTANT: Sorry, No flights found with your selected dates.

USER: Not an issue, thank you for the information.

ASSISTANT: Thank you for opting us.