I just received my ADP-001 and am trying to use it on my original 4.1 Willem (straight from the willem.org webshop) but am experiencing some problems. The software (I think I have 0.97j) can read the ID from my 89C2051 so I think it is inserted correctly. It also appears to erase the chip, but on read back I always get the same (non-empty) data back. Also, when writing it gives an error straight away at address 0.
If you can get ID, then the hardware setting seems fine. Plesase check all pin are in good contacting as well as the adapter to ZIF socket. The Software I used to test is 0.97ja. But you may try other version.
Ok, I feel very silly now. I had always assumed that "Vpp disabled" meant inserting a jumper to disable it, but it is the other way round. I had only used the programmed to read chips until now, so that's why I haven't noticed before. I can now erase, program and verify the 89C2051. It doesn't start yet in the target circuit, but that's probably not related to either Willem or the adapter.