The reason you're not attaining SP or LD for that matter, could be simply be your focusing too much. Clear your mind and relax, think only of your breaths and completely block everything else out. What usualy works for me (this has worked 100% of the time for me) is I usually get in my sleeping position (the one where you might come home drunk and flop on your bed xD) then I start to count from 1 to 100, and after every number, I say 'I'm dreaming'. Once I reach 80-90 without fail, I go into SP.

My state of SP is actually strange (I'm sure this happens to almost everyone), I feel an instant sensation and my whole body goes completely numb, and then my heart starts racing and racing and racing and I start breathing heavier and heavier and heavier. It's quite thrilling. The problem I have isn't reaching SP but the actual transition from reality to the dream world.