I have this working to a degree with a couple of issues, the main one being,
When I click on a category, the products are listed and the available filter options are shown.
Sometimes I filter on an option and the result is zero products even though results should be shown.
Do results only come back where the product's main category corresponds with the category being searched on?

To see what I mean, if you go here http://onestopglasses[dot]co[dot]uk/index.php?main_page=index&cPath=102
and select option 'Light Brown', no results will return despite it being available as an option on more than one of those products.

Any ideas?
Thanks in advance.