Amm.. check out this guide if you haven't already
viewtopic.php?f=42&t=116 And give as much more info as you can, like about OS, root folder, etc if you want help, otherwise it's just guessing from forum members. Post future related questions in that topic to get a relevant response, maybe it will help others that are searching as well. I'm guessing you missed step 5, but who knows what you did

PS: You don't need PlugY for SP if you use D2SE, i recomend it, even if you play on realm, it saves the trouble of reinstall/paching original game for classic or other mods.