protected function SetActivePageSort()
    {
        $this->sActivePageSort = $this->GetUserInput('pagesort');
        if (empty($this->sActivePageSort)) {
            //load default
            $this->sActivePageSort = $this->GetPageSortDefaultValue(); //default
            $this->SetModuleSessionParameter('pagesort', $this->sActivePageSort);
        } else {
            $bFound = false;
            foreach ($this->aPageSort as $iPsKey => $aPsVal) {
                if (in_array($this->sActivePageSort, $aPsVal)) {
                    $bFound = true;
                }
            }
            if (!$bFound) {
                //try to load from session
                $this->sActivePageSort = strtolower(trim($this->GetModuleSessionParameter('pagesort', false)));
                if (!$this->sActivePageSort) {
                    $this->sActivePageSort = $this->aPageSort[1]['id'];
                } //default
                $this->SetModuleSessionParameter('pagesort', $this->sActivePageSort);
            }
        }
    }