You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you at this moment?

USER: I am James Taylor want to visit HOU, can you book a ticket from DCA?

ASSISTANT: Sure, I will help you with this. Can you please provide your journey dates to proceed further?

USER: Sure, my travelling dates will be 08/20 and 08/22.

ASSISTANT: Wait a moment please.

USER: Ok.

ASSISTANT: James Taylor, there are no flight services available on this route on your provided dates.

USER: Ok, proceed with my booking. That's ok, thank you.

ASSISTANT: Thank you for contacting us.