You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Nicole Jackson here.

ASSISTANT: Yes, Nicole.

USER: I want to go to Denver DEN. Can you make my reservation from IAD>.

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

USER: My travelling dates are from 02/17 to 02/19.

ASSISTANT: There are no flights available on those dates, Nicole.

USER: It's ok. Thank you for your time.

ASSISTANT: Thank you for choosing us.