Why doesn't pagination work in the component for joomla 2.5 when using filters?

Question

PHP

I took the basis for the component here .
Even if I just take everything from the admin part and paste it into the site part (before that I rewrote it to my needs), then pagination does not work if the filter is applied - the correct address is written in the address bar, but the page is displayed the same. If the filter is reset, then pagination starts working. Maybe someone else has experienced something similar...