THIS SOLVED ALL MY PROBLEMS

No, this is no click-bate!

I had 2 big problems while retopo the face in Zbrush:
#1 My point would not stick to each other
and
#2 My points would sometimes not move when I was in 'W' move

So the solution is to:

#1 Use a slightly bigger brush (usually 2 or 3 would do the job)
and
#2 Unmask the vertices

Thanks to this magical thread:
http://polycount.com/discussion/119948/zbrush-4r5-unmovable-re-topology-vertices