New Off-line License comes up as expired

[derilium 0]

I have generated a new off-line license from my ESET endpoint license manager (I have 3 licenses left) the procedure works correctly but when I apply it to my closed network the client states its expired, even though I have 300 days left.

I have upgraded the antivirus to the latest version (7....) under guidance from my reseller and it still states its expired.

Any help with this would be greatly appreciated