Call Symantec or go online and open a ticket. They'll need a few more specifics but then anyone will to give you much assistance. I don't think I'd wait for an answer here before submitting a ticket. If you're asking here because they're not being very responsive, it might be time to move to a new vendor.
I am getting this error on multiple devices. Our license is valid and does not expire until November of this year. Any suggestions?