It probably isn't your fault, as I'm pretty sure SafeSysUpdater only checks if you have the right update pack from that site.
SafeSysupdater was designed for noobs like you, as it has more safety checks than normal Sysupdater (which has none at all).
So if you think you've got the right update pack, you can try your luck.
Okay, I've also found another source and I'll try it. Also, ever since I've joined I keep here about "that site" but I still have no idea what site it actually is. I know WHY nobody calls it by it's name but I still feel rather out of the loop.