You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you today?

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

ASSISTANT: Can you please share your journey dates?

USER: Ok, my itinerary dates are 12/26 and 12/28.

ASSISTANT: Wait for a minute. I am sorry to say that there is no flight found.

USER: Ok. No problem, thank you.

ASSISTANT: Thank you for reaching us.