In this task, you will be given a short story. One sentence from the story is chosen. Consider the events that happen after that sentence. Is any of them directly caused by it, or is made possible by it? You should write your answer in the form " A >causes/enables> B". Try to use phrases and sentences from the story to compose your answer when possible. Do not change the main selected sentence in your answer.

story: Lou bought a newly constructed home. He already submitted a change of address form with the USPS. Lou checked his box everyday for a month and it was empty. He called the post office concerned and found that they had his mail. They weren't able to send it because his new address was new.
selected sentence: Lou checked his box everyday for a month and it was empty.
Lou's mailbox is empty >Causes/Enables> Lou calls the post office