"Missing command error" in plug-and-screenshot

I am trying to take a screenshot in my cordova application. I am using https://github.com/gitawego/cordova-screenshot plugin.

  navigator.screenshot.save(function(error,res){
      if(error){
        console.error(error);
      }else{
        console.log('ok',res.filePath);
      }
    },'jpg',50);

      

        
        
        
      

    

console.error ('error') throws "Missing Command Error". Any help?