http://www.not5150.com/revphoto.htm the author makes some prescient points. activation does seem to trip a lot of beginning pr'ers up, as does the pr state itself. i know i struggled with both myself, i still do from time to time and i've been pr'ing for just over a year.
the part about pr'ing books for 3 weeks is a point i would consider Mandatory. if you haven't gotten the system to work for you, then try doing this. take 3-5 books on a subject you know nothing about and probably consider you can't learn, and photoread them every day for a month. incubate them and go through one activating method every day after about the first week (sr/dipping, mapping, etc.) you probably won't see any results for 2 weeks but in around the middle of the 3rd week, it'll all come together for you. I don't know why that happens but it does. I think it's because the brain is wired in such a way that it takes 3 weeks to acquire a new habit, so in order to override your old learning technique you need to 'break' pr in.
a simple way to keep the photofocus state: before you start pr'ing a book, close the book and look at the side. then shift your gaze past the book to the area behind it. the book should be in photofocus automatically. slowly open the book 1 inch and shift your gaze back to the book. then shift your gaze behind the book again and you'll notice the blip. continue opening the book and shifting your gaze. (hint: once the book is about halfway open, shifting gaze becomes harder because your eyes have to travel farther to go into pfocus).
if that doesn't work for you, remember that photofocus is actually the opposite of being crosseyed, so imagine both of your eyes moving away from each other and focusing on the opposite wall. that is photofocus in a nutshell.
activation is more complicated...lol! you'll have to keep drilling yourself on the course for activation tips. if only there was a sure way to activate spontaneously....ha! i wish 
