I'm pretty sure you're downloading tilesets that are not 1.21 or 1.20 or 1.23 compatible. It sounds as if you haven't played JJ2 for a while. You need to download the 1.23 patch or stop using TSF-only tilesets, if you want any tilesets to work for you. At least that's what I think. I'm not a JJ2 technical expert, I'm afraid.