Camera Extension not appearing in SmartDashboard

[dhe95]

Our team is trying to write our own custom image processing extension for SmartDashboard but whenever we compile and move the .jar to the extensions folder, nothing shows up in the add menu.

Here is the code we are using

import edu.wpi.first.smartdashboard.camera.WPICameraExtension;
import edu.wpi.first.wpijavacv.WPIColorImage;
import edu.wpi.first.wpijavacv.WPIImage;

public class VisionSystem extends WPICameraExtension {

    @Override
    public WPIImage processImage(WPIColorImage rawImage) {
        return rawImage.getRedChannel();
    }
}

Any suggestions?