Anti Virus

I have now installed the anti virus. I can’t seem to enable the “On Access Scanner”, have I done something wrong not going to the write place. I have clicked the Turn on button, and getting Error message, (Number STOAC017, Discriotion: Unable to perform requested opertation).
Need help. If it is all possible to send the respons to my email, I stil do not know how to use the form.
Sark