After much messing around, I just couldn't get it work with the light and kickercup technique. There was a wall there (which is actually what you see through the kickercup holes) that I just couldn't figure out why it was in the way.
Searching through the forums, I found out there was another technique that folks used to use before the light technique became more common. The idea is to have the kickers not on their normal surface but on an invisible wall floating above the actual surface. I tried it and it works perfectly! Here's what you need to do to fix this on BK 2000.
1. Create a wall named "145h" and set it to invisible with a top and bottom height of 145.
2. Place this wall above the top left corner of the table. You'll notice there are already there other types of walls similar to this one (the small squares next to each other) but for other purposes.
3. Make sure the kickers for the lock are of type "KickerInvisible".
4. Change the kickers' surface to "145h".
And voila! That should do the trick.