Problem with Filters

Hello. I have installed a OC 3.0.2 version in www.surgicare.gr. The filtrering does not seem to work at all.
I have made filters before in another site, in OC 2.3.0.2 and used the same technique. Create filters, enabled then in Category and then chose the correct one in the products.

In this site, I select a filter, press Refine Search and the page reloards with filter unchecked and all the products in place.
I went back to default template, but same thing happens. The products are at places in 2nd and 3rd level of Categories.

Is there any idea what could go wrong? Thank you very much for your time!