finally i found the solutions!
If in the contacts or timeperiods configuration you've got a "n" over the notification options (like w,r,c,u that stands for warning,recovery,critical ....) the notifications will not work. The "n" stands for NO NOTIFICATIONs, even if you've got, for istance, w,r,c,u,n , the N has the priority. Removed n, restarted nagios and that's it! it works!
Hope this post could be helpful to someone out there...i spent at least 10 hours of mylife following this issue...