Problem with making plugins with eclipse.

Alright, this problem has bit me on my ass for years now, and I still cannot fix it. Basically all it does is when I complete my plugin, and try to test it, it just shows up in the /pl or /plugins and it also says in the command prompt saying it loaded, but when I try the commands, it does NOT work. I looked at the previous owners work and it looks EXACTLY the same, everything, every part. But it just does not work. If I can get some help this would be great!

Copy and pasting is not the best way to learn java. Learn it, done it