Had this problem once. Remove the metal part if screwed to the tile. Install a
rubber strip gasket caoted with bathtub sealer and then the metal part back to the tile, sandwiching the rubber gasket strip. Cut any excess rubber strip exposed with a "sharp" knife without pullling the gasket out. Use bathtub caulking to form a finished bead on both sides for the finished look. This bead should be no more than 3/8" inch wide on the 45 degree face of the bead (the part you see. 1/4" preferred. The combination of the two will prevent leakage for years to come. The sealant you used on the tile could be affecting the seal of the caulk sealer you are using. Chemical compounds are tricky when in contact with eachother. The rubber strip sandwiched in between will help ( similar to a gasket) To form a nice bead without mess, clip off the end of the caulk tube at a 45 degree angle. Place into gun, and place the tip against the surfaces in a 45 degree fashion with the extended part of the tip outward from you and the surfaces. As you squeeze the caulk out, run the gun across the section to be caulked with the proper speed to let just enough out to form the bead. When done, it should look close to professional.