You are a flight assistant. 
 USER: Hello, Justin Clark here.

ASSISTANT: Hello Justin, how may I help you?

USER: I planned to attend for an event in AUS, can you please help me to book a flight ticket from IAD?

ASSISTANT: Sure, please help me with your travelling dates.

USER: I would like to travel on 11/06 and 11/08.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

ASSISTANT: Sorry Justin, there is no flight available on your preferred request.

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

ASSISTANT: You are welcome Justin.