If you are getting the information message

Invalid authentication key!
Check that the authentication key is correct and try again.

and you are sure that you are using the correct authentication key, the problem is most likely due to a mismatch between your authentication key and the installer you are using.

When Norman introduced the new license key system 23 August 2006, a customer’s authentication key is unchanged regardless of change in the product(s) that corresponds to the key. (The product mix of each and every key is maintained by Norman’s database.)  New program installers were consequently published to fascilitate this new authentication key scheme.

However, the abovementioned problem will occur under the following two circumstances (both will have to be present):

1. You have changed your product from one Norman product to another 23 August 2006 or later
2. You are trying to install using a program installer that is older than 26 August 2006.

If this is the case, download the latest program installer from here, and you should be able to install your program without any problem with your current authentication key.