If an exercise doesn’t feel right or the machine you are using is working a muscle other than the one you want worked, abandon it for the time being. It’s just a matter of your body not fitting that machine. It’s no big deal. Again, try different approaches to using the machine, stand instead of sit, lean in or out, sit backwards in it, whatever it takes to feel it. If that doesn’t work, like I said abandon it for now and come back to it another time. Free weights are a little different in that they allow you to use what you feel is the best range of motion and allow more freedom of movement. Incorporate free weights, machines and also cables and pay attention to what form or technique works.