Transmission oil cooling line

I am leaking trans fluid from the upper transmission cooling line at the fitting. Bought a new line and fitting but the new one is leaking too! Now I see that there is a “special” tool that you need to remove the line. I didn’t have any problem just screwing the fitting off. Looked simple just put the line through the fitting and screw it in. Did I mess something up or just missing a obvious step? Can’t find any instructions in chilton or haynes manuels. 95 Ford Tauras station wagon GL 3.0 V6 AXOD Transmission.

You missed an important step. The fitting has o-rings in it to seal around the line. You may have damaged the seals by installing the line first before the fitting. You need a new fitting. Install the new fitting first, and then ‘click’ the line into the fitting.