The "Advanced" section in the "Highlights&Shadows" brick has been deprecated with Aperture 3.3.
It will only be active, as long as you have an image in your Aperture library, that has been adjusted with the old pre-Aperture 3.3 adjustment.
To get it back, import an Aperture library that still has it.
See Kirby Krieger's post here:
I put an Aperture Library with a single image with highlight and shadow adjustments here for download:
Download and uncompress it if you like, then you can import it as a template to generate a preset.
Thank you for your prompt response. I have imported the image you sent and it's all successful. I have just purchased a Canon 5D MKll for lots of money – a lovely camera, but was losing the will to live when I thought I had lost sensitive Adjustment sliders which I use all the time. You have restored my software and my faith in digital photography and human beings all at the same time!
It remains hard to undertsand why Apple would update Aperture by removing very useful functions.
Hope all is peaceful on the Galapagos.
With best wishes