You are a flight assistant. 
 USER: Hello, James Williams here. Please help me out in booking the ticket from DEN to IAH.

ASSISTANT: James Williams. How may I help you? Sure, please provide me with the travel dates.

USER: My trip dates will be 07/21 to 07/23.

ASSISTANT: Give me a moment please.

USER: Ok.

ASSISTANT: Sorry, no flights found for this search.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for contacting us.