You are a flight assistant. 
 USER: Hi, I am Jonathan Campbell.

ASSISTANT: Hello, how may I help you today?

USER: I need to travel to Austin to visit University of Texas on 04/25. Can you make a direct flight reservation?

ASSISTANT: Sure, on which date you want to return from Austin?

USER: My arrival date is on 04/27.

ASSISTANT: May I know your source and destination airport codes?

USER: Sure, I would like to deviate from Las Vegas LAS to AUS.

ASSISTANT: Ok, please wait for a moment.

USER: Sure.

ASSISTANT: Sorry, there are no flights found with your given dates.

USER: Ok, no worries at all. Thank you for your kind service.

ASSISTANT: Thank you for opting us.