How to fix the unsecured avast?

I already uninstall my previous anti virus called avira, and replace it to a new latest version of avast when the installation is already done, it says UNSECURED YOUR SYSTEM IS NOT PROTECTED PLEASE USE THE FIX NOW BUTTON TO START PROTECTING YOUR SYSTEM. I tried clicking the fix now button many times but nothing happened! I went to my security center both of my firewall and authomatic updates are ON except the virus protection where it says NOT MONITORED. Can you help me and give me some steps on how to fix this? thanks...