After years of playing guitar I tried the spider exercise one day. I stared and stared at my ring finger but it didn't move. For some, finger independence can take a long time to develop.

I don't know what the instructors or truly proficient members will say but I can tell you what worked for me; I used a metronome set at a very slow speed (I think it was 40 bpm). By the end of a week of ten miniutes a day work all the fingers started to do what I wanted... the brain-muscle connection had finally kicked in. From there it was a slow weekly iincrease in speed.

Take your time, be devoted to practice, [u]relax[/u], use a metronome and start at a low bpm. It worked for me.

Good luck, have fun.