For me, I have an easy time building my legs.... I guess all the years of hockey and football paid off.
Give this a try:
20 rep squats!
Start with 1 25lb plate on each side and do 20 reps. Add another 25lbs plate and do anyother 20 reps, so on and so on until you can no longer can hit 20! When you are done with those, go over and do some leg curls 3 sets of 8-12 reps.
Next leg workout, substitute Hack Squats in instead of regular squats (20 reps again). Followed by SLDL.
I don't like to do Squats and SLDL in the same workout. I find once you start to life pretty heavy it puts a lot of strain on your back. Good form is key, but I want to avoid injury as much as I can, so on SLDL day I do hacks instead.
Try out something like that.
On squats and hacks, make sure you go ass to the grass. Your calves and hamstrings should touch at the bottom of the lift.
If you are having trouble with your technique, get someone to take a video of you squatting and then post the vid in here.