After installation plugin is not showing up

Hi everybody,

I am experiencing a “strange” problem.

When I install the “Sofa OpnPress – Publishing Platform” plugin,
I won’t be able to see it in the list of installed plugins, even if the installation was successful!
I got an error once saying:

Sofa OpnPress plugin was deactivated due to an error: plugin file does not exists

I installed it using the zip file download from themeforest.
I assigned, as a test, 777 privileges; and
overwritten the unzipped files of the plugin via ftp in the plugin directory of my server.
I can’t deactivate

But despite all this attempts nothing changed.

Anyone have any ideas? please