Emma,

At this moment, the way to make a good rendered image is:
- use version 3.0 or one of the v3.0 betas.
- use the command 3D view --> Create photo to make the render.

The AdvancedRendering plug-in was used during version 2.6, and served as a development tool. Its features have been incorporated into v3.0, so there's no need to use that plug-in anymore.

Please, try to render your image again as described above. Hopefully that solves your problem.
If not:
- share your file, so we can give it a try
- tell us all about your computer, OS, Java version, etc

Hans