I all verified Ken and it seems correct.

After that, I resintalled DNN6.0.1 because i found an old install zip. I installed it fine, no problem and i did exactly the same steps as 6.2.1. I tried reinstall 6.0.1 once more to be sure and no problem. So, I reinstalled 6.2.1 and i the problem came back.

Then, I think the dnn 6.2.1 install package is failed...

From my 6.0.1 instance, i installed the 6.2.1 Upgrade . It seems working great except for skins : my default skin doesn't appear. I tried to choose an other one from hostsettings but idem.
An other user has exactly the same problem, so i answered here :

http://www.dotnetnuke.com/Resources/F...

Thank you for help.

Hello Sebastian,

From SQL Serveur 2008, the Options tab mentions Level Compatibility : SQL Server 2008 (100)

My version is 10.0.4000.

I'm using the same SQL instance for 6.0.1 (finstall OK) and 6.2.1 (install KO). In both case, i created an empty DB, filled later from dnn install wizard.