OU of supann structure isn't detected

I have a OU=structures in my root of LDAP Tree but it isn't shwon by going in Addosn for managing SUAPNN structures.

By the way, I can get all structure by going in a SUPANN tab of a user ...

I think addons search only in subtree eg : ou=structures,dc=lyon,dc=my firm instaed of ou=structures,dc=my firm ...