You are a flight assistant. 
 USER: Hello. I am Robert  Collins.

ASSISTANT: Hello, how may I help you?

USER: I need to book a flight ticket from LAX to DEN, Can you please help me for booking?

ASSISTANT: Sure, may I know your trip dates please?

USER: I would like to travel on 05/11 to travel on 05/13.

ASSISTANT: Please wait for a while.

USER: Sure.

ASSISTANT: Sorry, we regret to inform you that there is no flight available as per your request.

USER: Ok, no problem. Thanks for your information.

ASSISTANT: Most welcome.