I don't see anything obviously wrong in either of the files.
I got the E21 error on my Beaver Mill one time when I used a certain plugin for the SmoothStepper, Greg had altered something for me but he must have also done something to the Step/Dir pulses as it would constantly give me problems, he redid the plugin and all was fine again so there was an issue somewhere with the timing.
It sounds like you may also be getting the same issue but whether it is the board outputting erroneous pulse signals or wiring I am not sure. With you only getting one direction that could be the way you have the axis set up, rotary axes can be set like that if I recall and if you wish them to go the opposite way then you need to command a negative move.