Empty with a copy loc. constraint to a bone

Hi all,
I am trying to use an empty totrack my back pack to the spine bone of my armature,
I have it set up so that it works in the forward and backward directions, but in the up and down directions, it does the opposite of what the bone is doing,
Anyone got any ideas?

if you want the back pack to move with the spine bone you can parent it to the particular bone

select the back pack - shift select the bone (when in pose mode)
then Ctrl+P - parent to bone

Thanks waylow,
I will give it a shot