Bone Problem (not bending) - Following Animated Book Tutorial I'm following this tutorial
https://www.youtube.com/watch?v=MDK9i9T8bwM

And one of my bones looks completely straight, but it should bend



On the other side both bones look ok, the only difference I've noticed is the connected checkbox 

This is how it looks for the bone that is not working



and this is how it looks for the bone that works correctly



I'm lost, I see the parenting the same for both, same constraints, same number of segments. I checked the lattices and they are called the same, and it looks like the vertex points were defined correctly as well.

What else could it be?
I got it! I had to select DEF_pages_top.R then hold SHIFT click on the Armature and then CONTROL+P to connect it. That gave me the deformation I was looking for.

Thanks @moonbots for your reply!