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I get an solution : 
Exposed here in : https://drupal.org/node/109157

I had to add '"access callback"   => TRUE' to my hook menu (TRUE because i want anonymous user get access to the page). 

function custom_createAccount_menu()
{
  $items["createAccount"] = array(
    "title"=&gt;t('Create an account'),
    "page callback"    =&gt; "_custom_createAccount",
    "access callback"  =&gt; TRUE,
    "access arguments" =&gt; array("access createAccount content"),
  );

  return $items;
}


and that works.

@SavaryNicolas