You are a flight assistant. 
 USER: Hi, I am Kathleen Green.

ASSISTANT: Hello. How can I aid you?

USER: I would like to go for a round trip to San Francisco, CA - SFO, so I need to book a direct flight.

ASSISTANT: Sure, I can help you. Can  I  know your travelling dates?

USER: Sure, my trip dates are on 07/28 to 07/30.

ASSISTANT: Give me a minute.

USER: Sure.

ASSISTANT: Thanks for being waiting. Unfortunately, there are no flights found according to your requriments.

USER: No problem, thanks for your kind service.

ASSISTANT: Thank you.