You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: Dennis Edwards here, can you please help me in booking the ticket from DCA to LAS? As I'm planning to visit Las Vegas.

ASSISTANT: Sure, may I know your planned travel dates please?

USER: Sure, my planned departure and return travel dates are 10/13 and 10/15.

ASSISTANT: Please wait for a moment.

USER: Sure, I'll wait for your response.

ASSISTANT: Sorry, there is no flight available on your requested dates.

USER: That's ok, thank you for giving the information.

ASSISTANT: Thank you for approaching us.