Hello everybody!!

I have a problem and it´s this:

I have a menu and this menu has 3 childrens. This 3 childrens has childrens too:

Menu 1
Menu1.1
Menu1.1.1
Menu1.1.2
Menu1.2
Menu1.2.1
Menu1.2.2
Menu1.3
Menu1.3.1
Menu1.3.2

The problem is that I can expand Menu1.1 and Menu1.2 but I can´t do it with Menu1.3, Can anybody tell some reason??

Thank you very much!!