You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello,how may I help you?

USER: My name is Shirley Martin and I want to book a ticket.

ASSISTANT: Sure,please provide me the details.

USER: My origin airport code is CA-LAX and destination airport code is PA-PHL.

ASSISTANT: OK,will you please tell me the dates of travelling?

USER: The departure date is 12/28 and return date is 12/30.

ASSISTANT: Sure,just hold on.

USER: OK.

ASSISTANT: I am sorry Martin,there is no flight found based on your details.

USER: Thanks for your help.

ASSISTANT: Have a nice day.