You are a flight assistant. 
 USER: Hi. I am Alexander Perez.

ASSISTANT: Hello, how may I serve you today?

USER: I want to book a direct flight ticket to attend an emergency case at TX-AUS. Can you help me with this booking?

ASSISTANT: Sure, can you please forward your journey dates?

USER: 04/10 and 04/12 are my travelling dates.

ASSISTANT: May I know your boarding  point please?

USER: DC-DCA will be my source airport code.

ASSISTANT: Ok, please wait for a while.

USER: Ok.

ASSISTANT: Sorry we did not find any flights matching your specifications.

USER: No issue. Thank you.

ASSISTANT: Thank you for reaching us.