You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you?

USER: My name is Deborah Turner. I want to book a ticket  to attend a meeting in DCA from IAH, please can you help me to book a ticket?

ASSISTANT: Yes, sure. Could you let me know your travel dates?

USER: My travelling dates are 02/21 to 02/23.

ASSISTANT: Sorry, Deborah Turner there is no flight on your preferable dates. Thank you for choosing your service.

USER: It's ok.

ASSISTANT: Bye.

USER: Thank you for providing  the information.

ASSISTANT: Your welcome.