need help with door handles

ok got a set of porsche polished door handles.now the part i need help with, ive to the lock out my existing handle but when matched up to the porsche handle it doesnt seen to fully slide in to give the flush look.so when you try to tighten the small screw at the back of the lock it doesnt due to the barrel not being in far enough. any ideas??????????????? is there a post on here about fitting these handles?????????????