You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you today?

USER: I am Ashley Harris need to book a ticket from DFW to ORD, can you please help me in booking a flight  ticket?

ASSISTANT: Sure, can I know your scheduled travel dates?

USER: My planned dates of travel are from Aug 04 to Aug 06.

ASSISTANT: Is there any class preference?

USER: I want an economy class ticket.

ASSISTANT: Do you have any other preferences?

USER: I would like to return in the evening.

ASSISTANT: Ok, please wait for a while.

USER: Ok.

ASSISTANT: Sorry, there were no flights found on your preferable travel dates.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for reaching us.