I just purchased Magix Music Maker Premium and when I try to activate my serial number nothing happens. Also when I try to click on the store, download sound pools, or subscribe to sound pools nothing happens.
Did you log in to your account from MMM? Nothing visibly happens when you enter the serial number. However, it unlocks things/features you can download from the store, after you are properly logged in. But if that doesn't work, then I don't know...