You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: Can you please book me a ticket from OAK to ORD?

ASSISTANT: Sure, I am here to help you. Can you please provide me your trip dates?

USER: My travel dates are from 04/30 to 05/02.

ASSISTANT: May I know your name?

USER: Patricia Lee is my name.

ASSISTANT: Lee, please wait for a moment.

USER: Ok.

ASSISTANT: Sorry Lee, there is no flight available on your preferred dates.

USER: Ok, no problem. Thank you.

ASSISTANT: You are welcome and thank you very much for choosing us.