PHP wamp error to load dynamic library

I have an error when I try add extension in PHP with  library in WAMP or XAMPP.
PHP warning PHP status: unable to load dynamic library
No se puede encontrar el módulo especificador

Put enviroment path in windows the path to library but this not works. You must reboot the PC to load the service Wamp the path. 


All work fine.

the library are wsf.dll