License key of Assassin's creed II shown incorrect by game launcher

I have purchased the licensed copy of the Assassin's creed II game and when i am installing the game, during the installation it asks for entering the License key of this game. But the License key of Assassin's creed II shown incorrect by game launcher every time. I tried this many time but the same problem occurs every time. Provide the solution for resolving this issue.

You are having the the disc of the Assassin's creed II game and you had purchased the licensed copy of this game but you are having problem in installing this game. The license key of Assassin's creed II shown incorrect by game launcher of the computer system. So i will recommend you to make sure that you are entering the key properly.

The license key of the game is provided with the Assassin's creed II game at the time of the purchase itself. So insert the license key properly when asked by the game launcher during or after installation of the game in the computer system. Follow the key properly given on the game disc. If the "-" during the license key if they are not separated by default when asked to enter.

If you have already used the license key of the Assassin's creed II game before in your computer system or in some other desktop system then this issue is occurring. I think this is the used copy of the Assassin's creed II game and because of that you are getting this problem. So i will advice you to contact to the UBI Soft for resolving this problem.

Make sure that you are typing the License key of the Assassin's creed II game provided with the game. Because there are product key and the serial number of the gaming disc also provided with the licensed copy of the games. So may be you are entering any other key except the license key of this game. So do it properly again and after that this issue will be resolved.