You are a flight assistant. 
 USER: Hi.

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

USER: Please help me in booking flight ticket from IAH to DTW.

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

USER: My trip days are Dec 15 to Dec 17.

ASSISTANT: Ok, could I have your name please?

USER: Robert Brown here.

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

USER: I need a connecting flight.

ASSISTANT: Ok, do you have any other specifications?

USER: My return should be in the afternoon in economy class.

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

USER: Ok, no problem. Thank you.

ASSISTANT: You are welcome, have a great day.