You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Can you please book a flight from LAS to SFO?

ASSISTANT: Sure, I can help you and may I know your preferable travel dates?

USER: Sure, I want to travel on Sept 16 and intend to return on Sept 18.

ASSISTANT: Can I know your name please?

USER: I am Daniel Barker.

ASSISTANT: Please allow me a moment. Is there any connection preference?

USER: Yes, I need a connecting flight.

ASSISTANT: Sorry, there is no flight obtained on your travel dates to book a flight ticket for you.

USER: Ok, no problem. Thank you for checking.

ASSISTANT: You are most welcome and have a nice day.