sep client giving a message"Protection definitions are unusable"

Hi All,

There is one more issue I am facing at most of the machines of my environment. Whenever I click at sep client icon, it shows a message"Protection definitions are unusable"& below that, under "Virus & Spyware Protection", a message reflects saying "Waiting for Updates". Although I tried to run a repair & after that tried to run intelligent update file too, but both of this didn't work. Please suggest a solution.

SEP version is 12.1.4013.4013

Thanks in advance.