I have applied the skin modifier then the mirror modifier.
And pass the mirror modifier first.

I get this:
![problem][1]

But I'm supposed have this:
![No problem][2]


What I did wrong ?

Thank to answer, sorry for my english.

  [1]: https://i.sstatic.net/0KCB5.png
  [2]: https://i.sstatic.net/Qylnt.png