Is the cage moving the chain over far enough for the outer ring to pick it up? It looks like the way that you currently have the height of the derailleur set the nose of the cage is doing most of the work...on my pile of reference junk the bottom edge of the inner cages show the most wear. That'd make me think that maybe that derailleur is not high enough above the rings. But, then again, I haven't messed with a lever-actuated derailleur, so maybe my reference material isn't old enough.