You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: My name is Katherine Lewis, can you please help me to book flight tickets from DCA to LAX?

ASSISTANT: Sure, may I know your trip dates please?

USER: I want to travel on Sept 23rd and Sept 25th respectively.

ASSISTANT: Ok, do you have any other requirements?

USER: Yes, I want to take off during afternoon time and my return time should be during evening.

ASSISTANT: Ok, please wait for a while.

USER: Take your time, but make sure to check for s connecting flight.

ASSISTANT: Sorry, we regret to inform you that there is no flight available as per your request.

USER: That's fine, thank you for checking.

ASSISTANT: My pleasure.