Tub taps still dripping after replacement of seat and cartridge

I have replaced every part of my bathtub taps, handles, cartridge, seat, diverter. I didn't tape it, and it leaked. I took it all apart and taped where necessary and put it back together, now I have a slow drip. I pulled the diverter to make sure no water was still in the shower head/line, and it still drips. This makes absolutely no sense to me as to where it could be leaking….help…..please.