You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how can I help you?

USER: I am Alexander Nelson. I plan to go for a weekend trip with my friends. Can you book a flight ticket for me?

ASSISTANT: Sure, may I know your travelling details?

USER: MY Boarding point from Washington, DC-IAD to Houston, TX-IAH. My want to starts from 08/19 and return from 08/21.

ASSISTANT: OK, please stand by I will check and revert you.

USER: OK.

ASSISTANT: Thanks for waiting. There are no flights on your requested dates. Thanks for reaching us, have a nice day.

USER: OK, thank you for your information.