Frustrating oil leak

[Sagesurfing]

I swear for the past 12 years I have had an oil leak from the oil pressure sending unit. It’s a Chevy 350z I’ve swapped out units. I’ve swapped out engines. I’ve tried with Teflon, without Teflon. I make sure to cute the tubbing each time. I’ve tried tightening more and tightening less. It always, always, always ends up leaking right from where the copper tubbing goes into the unit. What am I doing wrong at this point? And please don’t tell me to use plastic or some other material. This system should work. I just swapped to a longer unit so it’s easier to access. I use the ferrule correctly, it comes with the unit. I want to know what I’m doing wrong 🫤