Anonymous User and HS

I have a vocabulary Vocab used with hierarchical select.

term 1
-term 1.1
--term 1.1.1
--term 1.1.2
-term 1.2
-- term 1.2.1
-- term 1.2.2
term 2
- term 2.1
-- term 2.1.1

I create a field field_vocab used in different content types and in the register form.
HS configuration for this field :
-Save only the deepest term
-Force the user to choose a term from the deepest level

It works well as authenticated user but in anonymous user (in the register form) I have an issue :
when I choose :
[term 1][term 1.1] I have the choice for the last term between [term 1.1.1] and [term 1.1.2]
but if I choose :
[term 2] I don't have the matching terms but only [term 1.1] and then [term 1.1.1] or [term 1.1.2]

How I can allow anonymous user to access to the taxonomy ?

Regards,

Nicolas