Point of View- My Dilemma

So, I am currently working on book #2 now.  It is a very different kind of story than If I Know It's Coming.  This one is a mystery, horror, suspense kind of thing.  I have gotten some good feedback from another writer I am working with- Karlajean Becvar.  She wrote a very good YA book called The Seeing Stone.  You should all check it out. Anyway, she pointed out one of the many flaws in the book- the point of view.  

I knew that it was a bit of an issue already.  I wanted to write the book in 3rd person, but apparently it is wavering between limited and omniscient.  Obviously a problem.  Being that point of view might just be the single most important creative choice a novelist can make, I need to get it right!

The main character, Zach, needs to be the focal point, but at the same time, there are other characters that I want to see through as well.  What a predicament!  For those of you who have similar issues, please chime in here.  Or, if there are other creative choice dilemmas you have and want to share, I am all ears.  It could be an interesting discussion.