I did everything but again nothing! Only the existing plug-in appears,and not mine!...Some time ago my plug-in worked, and when for some reason change the workspace,my plug-in stop to work. I tried to restore( [:))] ) the situation, but nothing! [:-/]

According to Plug-in developer's guide, created a jar file at the plugins folder right? And when run it with the command:
java -jar /path/to/SweetHome3D-4.5.jar(or by double-clicking on it), nothing happens [:(] ! What am I doing wrong???