You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Patrick Williams here.

ASSISTANT: How may I aid you today?

USER: My airport codes for boarding the flight are HOU to IAD. Can you reserve a flight ticket?

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

USER: My preferable dates for travel are 02/20 to 02/22.

ASSISTANT: Please wait for a minute.

USER: Ok.

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

USER: Ok, not a problem. Thank you.

ASSISTANT: Thank you for reaching us, have a great day.