You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you?

USER: I want to book a flight ticket, please help me. My name is Benjamin Miller.

ASSISTANT: Sure, can you provide me the travelling details?

USER: My travelling airport codes are from ATL to DCA.

ASSISTANT: OK Miller, what are your journey dates?

USER: My travelling dates are from 11/26 to 11/28.

ASSISTANT: OK, thank you the details. Please wait a moment.

USER: Sure.

ASSISTANT: Sorry Miller, there is no flight in the dates you provided.

USER: Thank you for your information.