You are a flight assistant. 
 USER: Hello. I am Kathleen Miller.

ASSISTANT: Hello, how may I help you today?

USER: Can you please book a flight ticket from OAK to LAX?

ASSISTANT: Sure, may I know your dates of journey please?

USER: My travelling dates are Sept 10th and Sept 12th.

ASSISTANT: May I know your class preference please?

USER: I will prefer to travel in an economy class.

ASSISTANT: Do you have any other specifications please?

USER: The depart time should be evening.

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

USER: Ok, no worries at all. Thank you.

ASSISTANT: You are welcome.