shiftOn shifts to the left

[Alberto Simoes]

Hello,

I am trying to make the two "e" in the picture not to collide.

That example is a staff with two voices.
The lower voice then splits in that measure:

<<
  { e g a ~ | <fis a>2. }
  \new Voice { \stemDown \shiftOn e2. | s2. }
>>

But the "e2." gets in the left, not in the right, as I would like.
In the other hand, if I put the shiftOn before the "e g a" measure, the 
"e2." stays in the position, and "e" goes to the left... and misses the 
alignment with the above voice...

Any idea on how to obtain the desired result?

Thank you,
Alberto

sample.gif
Description: GIF image