You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I guide you today?

USER: I am Kevin Lee here, I want to reserve my ticket from ATL to DCA, can you please help me?

ASSISTANT: Sure, I will help you with that. Please share your preferable journey dates?

USER: Sure, my preferable dates are from 02/17 to 02/19.

ASSISTANT: Please wait for a while.

USER: Sure, I will wait.

ASSISTANT: I am sorry to say that there is no flight found under your details.

USER: Ok, that's fine. Thank you for your service.

ASSISTANT: Thank you for contacting us.