Apart from perhaps present day lack of mindfulness, ability to make wise decisions regarding finances or being careful with our desires versus our income, there are a few Suttas where the Buddha explains the Law of Kamma. In them it says things like, if you're generous, you will become rich later. If you are stingy, you will become poor later. So I would assume that if you lose money or that money won't come to you it would be that somewhere in your past you've been stingy.