You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you today?

USER: Sarah Lewis here. I am a journalist, I have to interview a celebrity at Dallas. Please book my ticket from DCA to DFW.

ASSISTANT: Sure, can you please share me with your dates of journey?

USER:  I am planning the trip on 04/27 and after that I will catch the return flight on 04/29.

ASSISTANT: Please wait for a moment.

USER: Ok.

ASSISTANT: Sorry Sarah, there is no flight found as per your travelling details.

USER: It's ok, no problem. Thank you for your information.

ASSISTANT: You are welcome always.