Build Screensaver for OS X

Hi,

I want to build a monogame screensaver.
If a rename my Screensaver.app to Screensaver.saver, I can install the screensaver,
but it shows a error message,

"monogame.samples.draw2D.MacOS-Screensaver it not compatible with the os-version.

I hope anyone can help.
Regards
Ronny