You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you today?

USER: I want to book a ticket from Los Angeles to Houston.

ASSISTANT: Sure, please share your travelling dates.

USER: Travelling dates are from Nov, 15 to Nov, 17.

ASSISTANT: May I know your airport codes please?

USER: Airport codes are LAX and IAH.

ASSISTANT: Which class would you prefer to travel?

USER: I prefer economy class.

ASSISTANT: Is there any specific time of depart and return are you looking for?

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

ASSISTANT: May I know your name please?

USER: My name is Samantha Lee.

ASSISTANT: We don't have any flight available which meets your journey criteria.

USER: Thank you.

ASSISTANT: Thank you for connecting us.