Installed my own extension but can´t find it in operator tree

Hello, 

I developed my first operator and installed it. IntelliJ shows me that that the build was successful and 
that the task "installExtension" is finished and i can see that the extension was loaded in the "About Installed Extensions" - menu. However I can not find my operator in the operator tree. Any suggestions what the reasons could be?

Best Regards 

DucAnh