Anti-virus autoconnect could not load the scan engine

I can't get Live update to work and I keep getting the following message - AntiVirus auto-protect could not load the scan engine.  Please run live-update to get the latest version.  But when I run live update, it says it occurred today, about 25 minutes ago, but the Anti-Virus Auto protect won't turn on, just keep sending the same error.  I have a newer mac laptop with Yosemite.  Help would be appreciated.  thnks