You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you now?

USER: Alexander Lewis here.

ASSISTANT: Ok.

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

ASSISTANT: Ok, may I know the trip dates please?

USER: My trip dates are from 08/11 to 08/13.

ASSISTANT: Please wait for a while.

USER: Ok.

ASSISTANT: Sorry Alexander, there are no flights found on your requested dates.

USER: it's ok. Thank you for checking.

ASSISTANT: Thank you for approaching us, have a nice day.