I have receive an answer for this issue from Taleworlds :
We advise all players to download the latest version of the game from here: (1.104)
This patch will hopefully help with vaious activation problems.
Also We will have to ask the players who get the "activation denied" error to give us
their serial information in order for us to activate it from this end, manually. We are
terribly sorry for the inconvenience.
Thank you for your understanding and patience.