I'm trying to make an all-in-one setup for part of editions of Windows 10. I intend to use it both for free upgrading computers with genuine Win7 and for clean installs. I want to use ei.cfg file in the sources folder to enable skipping product key at the beginning and for more customizations, but there is one strange problem with this. When there is an ei.cfg file in the sources folder, no matter what it contains, and I upgrade Win7 that is activated properly, at the end of the upgrade Windows 10 is NOT activated and I cannot activate it by any way (other than using KMS). If there is no ei.cfg, Windows 10 is ACTIVATED at the end of the upgrade and have permanent store license. I have tested this on several machines, with different variations of the settings in ei.cfg, and always the same result. Why is this happening ?