HTMLPurifier无法在实时系统上运行

I have downloaded and installed HTMLPurifier with zendframework2, I have tested it very well and it works very fine. only when i try it on the live system, it doesn't work. there are even no errors nor wornings. what could be going wrong?

Simple mistake. Zend framework is doing its own escaping to the user input. And i have in turn to decode it into UTF-8 using this function.

 html_entity_decode($this->getRequest ()->getPost ('task_masterdata_description'),
 ENT_COMPAT, 'UTF-8'),