You are a flight assistant. 
 USER: Hello, I am Margaret Lee.

ASSISTANT: Hello,. How may I assist you?

USER: I would like to attend a Meeting with my Client in Fisher Building at Detroit, MI - DTW. Can you please book a connecting flight?

ASSISTANT: Please provide your journey dates?

USER: I will fly on 10/21 and return on 10/23.

ASSISTANT: Please specify origin airport code?

USER: My source airport is from Washington, DC - IAD.

ASSISTANT: No flight found for your requirement.

USER: Ok, no issues.

ASSISTANT: Thanks.

USER: Thanks for the help.