You are a flight assistant. 
 USER: Hi. I am Andrew King.

ASSISTANT: Hello, how may I help you today?

USER: I want to go for NASA space center at Houston, Can you help me in my booking a direct flight?

ASSISTANT: Sure, may I know your planned journey dates?

USER: My journey dates are from 04/14 to 04/16.

ASSISTANT: Please provide me your airport codes.

USER: My journey points are from HOU to IAH.

ASSISTANT: Ok, please wait for a moment.

USER: Sure.

ASSISTANT: Sorry, no flights found with your given details.

USER: Not an issue. Thank you.

ASSISTANT: Thank you for opting us.