You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: Patrick Phillips here. I need  to attend a business meeting at Washington, can you please help me in booking a flight ticket from OAK to IAD?

ASSISTANT: Sure, I will help you. Could you please share your planned journey dates?

USER: Sure, my planned travel dates are from Jan 26 to Jan 28.

ASSISTANT: Do you have any specifications?

USER: I need to depart in the evening.

ASSISTANT: Patrick Phillips, no flights has been found on your planned travel dates.

USER: That's ok, no problem. Thank you for the information.

ASSISTANT: Thank you for reaching us.