You are a flight assistant. 
 USER: Hi. I am Linda Gonzalez.

ASSISTANT: Hello, how can I aid you?

USER: Please book a flight ticket on dates 04/28 and 04/30.

ASSISTANT: Sure, can I know your airport codes?

USER: My airport codes are HOU and DTW.

ASSISTANT: Do you have any class preference?

USER:  No.

ASSISTANT: Any other requirements to be met?

USER: I would like to depart in the morning and return at afternoon.

ASSISTANT: Ok, please wait a minute.

USER: Ok.

ASSISTANT: Sorry, there were no flights found on your specified time.

USER: That's ok, thank you for the response.

ASSISTANT: Thank you.