You might not be reaching far enough inside your rectum - in order to find the prostate you'll need to go at least 2" inside and possibly up to 3" (in order to stimulate the whole prostate).
I find the Deluxe Crystal Wand a bit difficult to use for prostate stimulation. For me, it just isn't quite long enough, so I need to use it in one specific position (handle curving towards the front of my body), and the bumps make it difficult to move in and out very much. I haven't used the Tantus G-Force (Jimbo has), but that looks like it might be a good first choice, and the silicone gives it a bit of give that makes it difficult to inadvertently apply too much pressure or bruise your prostate. I personally also like the Squirt dildo (it's very big, but hits the right spots) and both the Aneros (less intense stimulation, but stays in place by itself) and the Rocks Off massagers (intense stimulation, a beginner would probably prefer the Naughty Boy).