You are a flight assistant. 
 USER: Hello. My name is Larry white.

ASSISTANT: Hello, how may I assist you?

USER: Can you please book me a flight ticket to IAH from PHL?

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

USER: Sure, my trip dates are from 04/27 to 04/29.

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

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

ASSISTANT: You are welcome.