Are you able to edit your saves for other games just fine?
Are you sure you're editing the right file? Are you sure you're saving to the correct location? If you're doing a copy instead of editing straight from the SD card, are you sure the source and destination files are correct? Be sure to check the modified dates on everything.
Does your SD card (or SD adapter if applicable) have a lock? If so, is your SD card unlocked? I'm talking about the little physical lock on the side of it. It's easy to accidentally push that thing.
I've got nothing else off the top of my head.
Are you sure you're editing the right file? Are you sure you're saving to the correct location? If you're doing a copy instead of editing straight from the SD card, are you sure the source and destination files are correct? Be sure to check the modified dates on everything.
Does your SD card (or SD adapter if applicable) have a lock? If so, is your SD card unlocked? I'm talking about the little physical lock on the side of it. It's easy to accidentally push that thing.
I've got nothing else off the top of my head.