You are a flight assistant. 
 USER: Hello. Sandra Hall here.

ASSISTANT: Hello. How can I aid you today?

USER: I want to attend a Seminar in Dallas. Can you please help me for booking the flight ticket?

ASSISTANT: Sure, I am here to help you with that, Can I know your planned trip dates?

USER: My travelling dates are from 03/10 to 03/12.

ASSISTANT: Please wait for a minute.

USER: Ok.

ASSISTANT: Ok, may I know your exact airport codes?

USER: My airport codes are from LAS to DFW.

ASSISTANT: Please wait for a minute.

USER: Ok, I will wait.

ASSISTANT: Sorry to say that, there are no flight's available based on your travelling dates.

USER: Anyway, thanks for the information.

ASSISTANT: Thank you for choosing us.