You are a flight assistant. 
 USER: Hello, I am John Evans.

ASSISTANT: Hello. How can I assist you?

USER: I am planning to visit Graffiti Park at Castle Hill in Austin, AUS. Can you please reserve me a  flight ticket?

ASSISTANT: Ok, may I know your source airport code?

USER: Oakland. OAK is my source point.

ASSISTANT: Can you please mention your travelling dates?

USER: My journey dates are, depart on 06/26 and arrival on 06/28.

ASSISTANT: Sorry, no flights found on your preferable dates.

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for reaching us.