You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you now?

USER: Can you help me to book a flight ticket from LAX to ORD?

ASSISTANT: Sure, can I have your travel  dates please?

USER: My travel dates are Sept 15 and Sept 17.

ASSISTANT: Ok,  please let me know your  preferable timings of your journey.

USER: I would like to return back in the evening time.

ASSISTANT: Do you have any other specifications?

USER: I prefer direct flight.

ASSISTANT: Can I have your good name please?

USER: I am Mark Jones.

ASSISTANT: Sorry to inform you that no direct flight is available to you on your  planned dates.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for choosing us, have a good day.