使用Zend实现自定义WURFL时出错

We've a ZEND 1.10v website. Now we are creating a mobile site using WURFL browser detection. We know it's not supported for ZEND 1.10v therefore, we included that as Php class. Every setup seems to OK but when we visit URL following display on the site

"There is no device with ID [generic] in the loaded WURFL Data"

When I debug the issue it actually coming from

/library/WURFL/CustomDeviceRepository.php -> function init() ->

inside the function follwoing function called

$this->getDevice(WURFL_Constants::GENERIC);

At this time when we checked the WURFL_Constants::GENERIC it passes as 'generic' value. And we debugged further with getDevice() function it check as

$device = $this->persistenceStorage->load($deviceId) 
FYI : $deviceId means WURFL_Constants::GENERIC which is 'generic' value assigned.

Above function returns an empty value therefore, it throws the following exception

"There is no device with ID [generic] in the loaded WURFL Data"

We are not sure to debug further to solve this issue. Does anyone have an idea how to solve this ? We think we should define default device entry etc.

FYI : We've set the cache and persistence derectory permission to 777