public function loadStatus($serviceName, $attributeName) {
        // make sure extension is loaded
        $this->checkExtension();
        // try to load the data
        $stats = $this->load($this->cachePrefix . $serviceName . $attributeName);
        // if the value loaded is empty return empty string
        if (empty($stats)) {
            $stats = "";
        }
        return $stats;
    }