You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I am Angela Harris from New York. I want to visit Dallas next week for attending a business meeting there. Can you please book a flight ticket from LGA to DFW?

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

USER: Thank you for your response, I want to take off on 04/21 and please confirm my return ticket also on 04/23.

ASSISTANT: Please wait for a moment.

USER: Ok.

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

USER: Oh! It's ok no problem. Thank you for your information.

ASSISTANT: You are welcome.