Rotating the bone doesn't move the object - blender 2.63

Hello everyone!
I’m new to Blender and on this forum so i apologize if i’m asking in the wrong place.
I started making a simple animation of a box opening the flops. I’ve done everything as the tutorial said (at least i think i did, because it’s for the older version of blender), and it just don’t work. When i switch to pose mode and try to rotate the bone, the flop doesn’t move with it. Two times i managed to get one flop moving (each time different one), but not the other three.

the procedure was something like this (after the flops and bones were created and at its place):
-in object mode select bones and box
-press ctr+p, click “object”
-select box
-switch to edit mode, select outer vertices of front flop
-in object data created new vertex group, named it “front”, clicked assign button
-switch back to object mode
-select the front flop bone, on the right under the “bone” changed bone’s name to “front”

the procedure for each flop was the same (except the name).

What am i doing wrong?