You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: Can you please book a flight ticket in business class?

ASSISTANT: Sure, please mention your travelling airport codes.

USER: My airport codes are, DTW to HOU.

ASSISTANT: Can you share me your travelling dates?

USER: My journey dates are, depart on Apr 21st and arrival on Apr 23rd.

ASSISTANT: Do you have any specifications?

USER: I prefer a flight with single connection.

ASSISTANT: Can I know your good name?

USER: My name is Donna Walker.

ASSISTANT: Sorry, no flight are found on your travel dates.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for reaching us.