You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Gary Walker and I want to book a flight ticket to attend a seminar which is  going to held at TX-DFW from CO-DEN.

ASSISTANT: Ok, please provide your journey dates for further process.

USER: My traveeling dates are from 12/04 to 12/06 with direct flight.

ASSISTANT: Ok, please wait a minute.

USER: Ok.

ASSISTANT: Thank you for waiting, sorry to inform there was no flight found matching your details.

USER: No issue. Thank you.

ASSISTANT: Thank you for choosing us, have a nice day.