> ... but when I use the SaveGame Installer, I get an Error (Ret = -1)
FWIW: This infrequently happens to me. To fix it, put the DVD in the drive and the SD card in the Wii *before* turning on the Wii power.
[if using the Install approach, I find it quicker to unplug the power cord between test runs; which also ensures the Wii starts with a clean slate]