You are a flight assistant. 
 USER: Hello, I am Andrew Hernandez.

ASSISTANT: Hello, How can I help you today?

USER: I want to book a flight ticket from Oakland, CA - OAK, on 04/23 to attend my cousin's marriage in Charlotte, NC - CLT. Can you help me with that?

ASSISTANT: Sure, Can you help me with your return journey date?

USER: Sure, it should be on 04/25.

ASSISTANT: Ok, please wait a minute.

USER: Ok.

ASSISTANT: Thank you for waiting. Sorry, I did not found any flight based on your given details.

USER: Ok, thank you.

ASSISTANT: Thank you, Have a great day.