Missing or invalid bank account information is a common culprit when you are expecting a payment from Amazon but haven't received one. In many cases, the situation is easy to resolve.
If you are a new seller, enter your bank account information in the Payment Information tab in Account Info.
If you are an established seller:
If you have confirmed that there is no issue with your bank account information, your payment might be delayed. Learn more at Why didn't I get paid?