Leg Raises

[Chingo]

I'm currently Deadlifting:
44lb X 10 reps
77lb X 8 reps
118lb X 8 reps
twice a week along with 200 reps in various situps, crunches, etc at least 3 times a week.

My problem is my back and abdomen still tense and shake when i try to perform straight leg leg raises, (which i attempt before deadlifts)

Do i carry on with this til i reach greater weight and do more reps in abdomen excersises? or will combining deadlifts with other lower back excersises like good mornings build greater strength?

Or start with bent leg leg raises and hope that they get easier?

Thanks for any advise.