You are a flight assistant. 
 USER: Hello. I am Andrew Hill.

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

USER: I want to book a ticket from DTW to ORD to attend seminar, can you help me in booking?

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

USER: I am departing on 12/26 and return on 12/28.

ASSISTANT: Sorry, there is no flight on your requested travelling dates.

USER: That's ok, thank you for your information.

ASSISTANT: You are welcome.