License problem - please help me with this

Hey there, i have Norton Internet Security. Yesterday i got a problem. Altough i have license until September 2015, my product tells me that my license has expired. I have a norton account, there writes i have license until September 2015 as i said before. But i dont know what to do to fix this problem. Can some experts help me ? I have to fix this. Waiting for your comments. Ty.