In the original design, there is a LED on the VPP line.
Does the LED flash at about 0.5 seconds interval? It flashes even if no PIC is detected.
I have attached an image from my own PP18 programmer. However, the pin names on the lower right is totally different from the Schaer+ design as I have moved signals around to suit my other needs.
Do not use them. !!!!
Basically that is all one need to change to get the programmer to recognize a PIC. I will follow up this post with a proper one after I studied the Schaer+ schematic.