You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you now?

USER: Can you please help me with booking a flight ticket from IAD to DFW?

ASSISTANT: Sure, I am  happy to help you with that. Can I have your  travel  dates please?

USER: My travelling dates are from Aug 04-06.

ASSISTANT: Ok,  please  let me know your  preferable timings of your  journey.

USER: My depart has to be in afternoon.

ASSISTANT: Do you  have any other specifications?

USER: I would be comfortable with single stop over.

ASSISTANT: Can I have your  good name please?

USER: Ashley Harris here.

ASSISTANT: Sorry to inform you that no flight is available to you on your  planned dates.

USER: No problem, thank you for the information.

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