Rank - LP issue

ok... so when i win, i gain the minimal LP, yet i get good grades. i lose more LP, when losing then gaining when winning... no i do not believe its because i dont belong in the rank category, because im already at at very low rank. i did my 8 games of rank fro placement and it seemed fine, but once i got my final, thats when it started acting up with the LP. it tell me this is where you start to climb/placed, then tell me im not good enough this placement, lose lot sof LP? it doesnt really make any sense... almost impossible to climb... please help riot and explain what is happening