I installed the rear derailleur shifter cable on the wrong side of the clamp's tab. Then I couldn't get both the large cogs and the small cogs to shift cleanly, only the big half or the small half of the cogs.

If you look at the clamp bolt from the top, where the hex wrench fits in, there's a flat plate with two tabs. One tab fits in a hole in the derailleur body. There's a groove in the bottom side of the plate where the cable should go. It's to the left side of the other tab, not the right side.