Odds are you don't know OO
Many believe that object-orientation comes from the use of object-oriented programming languages. It doesn't. OOPL's merely allow you to implement an OO DESIGN! Object-Orientation is mostly a DESIGN matter that you can use OOPLs to implement. It makes zero sense to use an OOPL when your decomposition is a functional decomposition. In fact, you're creating a MESS every time you do so.