Delete trainer and all files in
Learn how to make your own Trainer Cleaner for the above paths Here. Link
Reboot PC to clear excess memory, get a fresh copy of latest trainer and extract it. Run trainer as admin, read the instructions and try again. At times, a new game may be needed to resolve failed options if the data in your save file was altered. Use on a new game and test the option. If it now works, quit to main menu and load your save and try it again. May also need to run the game without the trainer first and play a bit so the save file gets updated to use possible new values.<
Out of curiosity, are you using the Book of Reincarnation to reallocate the stat points that you can legitimately earn before doing this, or are you editing the stats after you have used all available points?
I have tried getting all the allocated points back through the Book of Reincarnation before editing my stats and applying the refunded points on top of the edited stats. Even with the method you've described, I have, unfortunately, been unable to make the edited stat values stick.
From what I've been able to see the game tracks your level number with three seperate addresses. You can change two of them, which is what the trainer does I think, but if you change the third the game quits back to menu and busts you down to level 1.