Guesses

1) My adaptor board has 2 connectors; 1 handles 8-18 pin PICs and the other handles 20-40pins. Perhaps the connector is connected to the wrong place.

2) Again, the orientation for programming 8-18 pins is one way on the zif and for 40 pinners is the other way. ie: pin1 for one matches ZIF 1 and pin 1 for the other type matches with pin 21.

3) Programmer is not turned on(very unlikely)

4) You've managed to blow the device.

Good luck

JF