You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you at this moment?

USER: I am Donna Moore. I would like to celebrate my birthday at Chicago, can you please help me to book a flight from DEN to ORD?

ASSISTANT: Sure, I will help you. Please send your travelling dates.

USER: Sure, my travelling dates are 10 Oct and 12 Oct.

ASSISTANT: Do you have any requirements to be met? Sorry Donna Moore, there is no flight available on your travelling dates.

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

ASSISTANT: You are welcome, have a nice day.