I have TinyBrick Fast catalog extension installed and navigation does not work in magento

I have TinyBrick Fast catalog extension installed and Improved Layered Navigation does not work, please open this file

app/code/community/TinyBrick/FastCatalog/Block/Layer/View.php

and replace this

Mage_Block_Catalog_Layer_View

with this

Amasty_Shopby_Block_Catalog_Layer_View