Thanks for your answer Vark! I did what you recommended but nothing changed and the error persists.
To resume, the plugin works fine at the frontend site but in the administration panel is where I encountered the error, through the console tool in Chrome.
This error is making the Desktop fail showing some features, and Adminimize plugin also fails showing options. When I deactivate the plugin, it all works fine.
My WordPress installation is 4.0, the spanish version.
Image: https://cloclobuenosaires.com.ar/screen.jpg