You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Mark Rodriguez here.

ASSISTANT: How may I help you at this moment?

USER: Please help me out in booking the ticket from IAH to DTW.

ASSISTANT: Ok, I will help you with that. Can I know your travelling dates?

USER: My trip dates will be 08/28 to 08/30.

ASSISTANT: Do you have any other specifications?

USER: My depart time must be in the morning.

ASSISTANT: Please wait for minute.

USER: Ok.

ASSISTANT: Sorry to say that, there are no flight's available based on your travelling dates.

USER: No problem. Thank you.

ASSISTANT: Thank you for approaching us.