There are serveral versions of willem, so this may not all apply but here are some tips. Your adapter may not look exactly like the one in the picture (mine doesn't), but it should have 27c400 stenciled some where on there so you know it's the right module. The program will prompt you to install the module, but can't tell if you have or not. So as long as you have it plugged in, ignore the message.
You need to match the switches you see on the screen with the switch settings on your board. Mind which is #1 and the oreintation of your board (up or upside down as you match the screen). If your willem has USB, you probably need to plug the USB cable in. It get's power from the USB for programming voltages. Also the eprom on my module seats to the bottom of the chip socket leaving the top to pins open. If you have it seated to the top, you'll get trash when you read. I'll try to diagram what I mean but the text editing here is tough to work with....
Pin 1 and 42 open at the top of the socket
0 = open @ = eprom legs
0 _open 0
@ rom @
@ rom @
@ rom @
@ rom @
@ rom @
@ rom @
@ rom @
Plaz