Q:

Filtering works on search page and doesn't on category product list

I am working on a Magento store and edit the code of another programmer. Now I runned in a problem. Filtering from layered navigation works on the search page and doesn't work on the page with products of a category.
Description:
Let's say I have category Shoes, with the attribute Color. 2 Products

Allure A302M, white color
Allure 212M, black color

If I search Allure, it finds those products. When filtering white color it finds A302M model. So Filter on search works. Now if I open category shoes and choose white color, filtering doesn't work, it find all shoes.
I found a custom module in code/local and removed it, but no change. What can be the problem? Maybe attribute configuration is wrong?
Configuration:

A:

Well I got it working. Don't know if this is a problem specific to this case or of Magento, but it worked after I changed the category value 'Is anchor' to yes.

