Why"The Defense+ security level is set to Inactive"?

In defense+ sittings I have set to “train with safe mode”,why summary screen still show “The Defense+ security level is set to Inactive"but not"The Defense+ security level is set to Train with safe mode” in “Proactive Defense” section ?Why Inactive?What does it mean? I can’t find answer in “help”.
please help.

My guess is that it (the Summary) hasn’t updated properly. Have you rebooted since the Defense+ level was set? There is also the possibility that you did not click the “Apply” button on the Defense+ Settings dialog. Try this: on the Summary page, click on the underlined completion of “The Defense+ security level is set to…” and that will open up the Defense+ Settings dialog. Set the Defense+ level there and click on the “Apply” button.

I have used this firewall for a week,so the rebooted problem don’t exist,the other metho you said I had used,it didn’t work.