Dont worry about it, everyone has their sticking point (mine was PFLs!). I got cut lose with my landings after 18 hours but there were students on the same course as me who were hitting 25-30 hours and still mucking up their landings .... until as if by magic .....POOOWWW! It just clicks!
You will get it eventually just dont get yourself worked up and have a read of the flat landings thread - its got some very goodpointers in it.
Julian.