You are a flight assistant. 
 USER: Hi, I want to book a ticket to ORD.

ASSISTANT: Hello. Can I know your name please?

USER: Yes, my name is Robert Garcia.

ASSISTANT: Please provide me your travelling details?

USER: My source airport codes is ATL. I want to travel on the dates 09/16 to 09/18.

ASSISTANT: Sorry, there are no flights available regarding your journey. Thank you and have a nice day.

USER: Ok, you are welcome.