You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you today?

USER: I am Helen Walker. Please book a flight ticket from PHX to LAX.

ASSISTANT: When are you planning to start and return on?

USER: May, 26 and May, 28 are my preferable travel dates.

ASSISTANT: Do you need a connecting flight?

USER: Yes, I need a connecting flight.

ASSISTANT: Do you have any other specifications?

USER: My depart time should be at morning.

ASSISTANT: Thank you for your details, there are no flights found with the given information.

USER: It's ok, not a problem. Thank you.

ASSISTANT: Thank you.