This article is from the Apple II Csa2 FAQ, by Jeff Hurlburt with numerous contributions by others.
The official name is the Videx Keyboard Enhancer. It replaces Apple's keyboard encoder board underneath the keyboard. Besides providing true U/ L capability (with the Shift Key), it had a small (10-20 character) buffer and supported programmable macro keys. I had one on my ][+. I remember a couple of wires had to be run to the motherboard. One enabled true Shift key usage. The other I can't remember. If you don't have a wire running to an IC on the motherboard, that explains why your Shift key isn't working. It could very well be the same spot where the "traditional" Shift key mod is made. By: Paul Creager