I don't understand how SD Menu works for the Wii AT ALL. I tried to MOVE channels to the SD CARD and I delete the game from the Wii main menu channel and it FAILS to LAUNCH from the SD CARD. I really WISH someone could HELP!! I APPRECIATE ANY INFO. THANKS.
-Steve
The most common reason I've seen for this is that people moved the games onto SD from one Wii (or Wii U) console and then tried to access/play the games on a different Wii console. When you download a game, it actually gets locked to that specific hardware so the SD card won't work on other consoles - although you will be able to see the games stored on the card.
It's also possible that your SD card isn't supported. Things should work with any normal SD card, or an SDHC card that is 32 GB or smaller in size.
I've also seen games fail to launch just because there is corruption on the SD card. Unfortunately the only way to get your games back in this case is to re-download from the Wii Shop Channel, format the SD card, and try again. (But maybe try using the Copy option and launching from SD that way instead of using Move. That way if it doesn't work, you won't have to re-download the game.)
If none of those comments help, maybe post more specific details about what happens when you try to launch the game. Is there an error message shown?