I buy the cheapest ones I can find and they work pretty well. Are yours leaking around the edge or are they dripping? If they are dripping you can unscrew them and put a drop of vegtable oil in and rescrew together. If they are leaking around the edge? I use JB Welds - Water Weld Epoxy Putty sold at Lowe's. I don't sand first as directions advise but I let it dry after application for 12 hours before using. It gets hard as concret and no more leaks and chickens can't pull it off, like they do to silicon caulk.
You haven't said what you did so I have no idea what could be going wrong.
I made sure I had the right drill bit (the directions called for an unusual size), the push-in style nipples, and a standard 5-gallon bucket. I then followed the installation instructions. No leaks here.