Norton Safety Minder is not blocking sites

I have the NSM (Norton Safety Minder) installed on two computers, and the two have two users. One user is a child who uses two computers. A computer installed Windows XP Professional and the other windows seven ultimate. The NSM installed in xp is working properly. But the windows seven is not blocking sites the computer user. It only makes the control of access time. Have reinstalled the NSM more than three times does not solve the problem. What may be happening? I use windows seven ultimate.
Regards,