You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, do you need any help from us?

USER: I would like to attend a meeting at Los Angeles, please help me in booking a ticket from IAD to LAX.

ASSISTANT: Sure, could you please share your departure and arrival day?

USER: My planned journey dates are on Dec 24 and Dec 26.

ASSISTANT: Ok, could I have your name please?

USER: My name is Mark Evans.

ASSISTANT: Ok, do you need direct or connecting flight?

USER: I need a connecting flight for my trip.

ASSISTANT: Ok, do you have any other specifications?

USER: I would like to depart in the morning.

ASSISTANT: Sorry, there is no flight with your requested time.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: You are welcome, have a great day.