Search kb article don't work as it should

Hi.

We have some trouble with Kbs search on our ServiceDesk portal.

All article created after April 2013 can't be found with this search. When we expand kbs categories, we can see all articles and open all of them. We haven't any problem to access these article but they are never in serach result.

We thought that it cas due to permission but result is the same even with all access to all user or with our adiministator account.

In sql database, article have the same configuration. we don't find what cause this problem.

Any ideas?

Sebastien