You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How could I serve you?

USER: Can you help me in booking from OAK to PHL, as there is a business meeting to attend?

ASSISTANT: Sure, may I know your planned travel dates?

USER: My trip dates are May 10 to May 12.

ASSISTANT: Do you need any connecting flight or direct flight.

USER: I need a direct flight.

ASSISTANT: Can I know your name please?

USER: I am William Green.

ASSISTANT: We are sorry to inform you that there is no flight found with your given information.

USER: No issue, thank you.

ASSISTANT: Thank you.