I re-read Daniel's comment. You do have to seat the left bearing against its lip inside the wheel hub. This gets it low enough where it holds the spacer just a little loose but allows you to install the dust seal above.
Steve
Make sure they are both seated against their inside lip on the wheel, otherwise when you torque down the axle the bearings will be in a bind. (center race compacted against the spacer, outer race not *quite* in the right place). They won't last long if they are not properly seated.