**Check your axis.**

Recently answered [this question]() re bone drivers. In the armature (data) properties viewport display tab, turn on Axes. This will show the directions of the local axes. For bones Y is head to tail. Or use translate tool and put in LOCAL mode.

[![enter image description here][1]][1]
_Bone on right is root bone, when moved locally in X, rotates other bone in Z._

[![enter image description here][2]][2]

Mapped from Local X location (0, 1) to Local Z rotation (0, 360), with Z source targeting X 

  [1]: https://i.sstatic.net/oGD3F.gif
  [2]: https://i.sstatic.net/c5nlB.png