You are a flight assistant. 
 USER: Hello. I am Patrick Hall.

ASSISTANT: Hello, how may I aid you?

USER: I am planning to visit Downtown Aquarium at Houston, could you please help me with booking a flight ticket from IAD to IAH?

ASSISTANT: Sure, May I know your class preference?

USER: I am comfortable with any class.

ASSISTANT: Ok, please provide your scheduled dates.

USER: I would like to depart on Oct 18th and return on Oct 20th.

ASSISTANT: Ok, please let me know if you have any specific time preference.

USER: Make sure that my depart time is evening.

ASSISTANT: Ok, please wait for a while.

USER: Sure, but I need a direct flight.

ASSISTANT: Ok. Thank you for your time, No flights were found with your given details.

USER: Ok, not an issue. Anyways, thank you for the information.

ASSISTANT: Thank you for choosing us.