As to what is causing the display malfunction I don't know. I can say that the display you are using is identical to mine and works. Therefore if the wiring is correct (and I would recommend you double check it as the diagram Zimmer made is simple but unfortunately reused a few colors leading to possible pin confusion. I would recommend relabeling them and using only one color per connection. If it still does not work, then your display may be defective. The only modification I made to his setup was to reverse the encoder's A and B signal lines to change the cursor direction relative to the knob rotation. Mine was reversed for my "feel" and as we do not have access to the firmware to change the code, reversing the analog signal side was easier (probably easier either anyway).