It seems like a common problem for Note II. Because the charging port is too far in, the micro usb cannot be plugged far enough to stay put. Mine sits really slug. I don't know if Samsung changed the port or the cable. One easy fix is to trim some plastic off the cable so it could be push further into the port. Or use a different cable than the one supplied.
But before you try anything, make sure your cable is plug all the way in. When you first push it in, it looks like it stopped and it would be charging but the cable could fall out easily.. but you could push it again and you will hear a click and it will be in there for good. At least that's how mine work.