Skylanders: how does the autosave work?

My son is playing "Skylanders: Spyro's Adventure" on an Xbox360. Now - I know the game is supposed to autosave each chapter and in some other particular occasions. However, he got to chapter 8, turned off the game and no saved game was there. I also tried playing a couple of chapters, turning the game off and had everything reset.

Before crying foul, I am quite sure there's something wrong with what I do. But I don't really know what: I play normally for a couple of levels, then press Play and choose Exit. When I restart the Adventure mode, I only have one option, to start a new adventure.

How do you make the game save in Skylanders?

Solution 1:

I figured it out myself:

You have to sign in with a user, otherwise the game will not save (but will not warn you that it is not saving).