[PyQt] Can i use Qt's codec plugin?

[DDGG]

Hello friends!
I want load a Qt's codec plugin at the runtime of my PyQt application.
There are three lines in my source file:

plugin = QtCore.QPluginLoader("C:/Qt/4.3.1/plugins/codecs/qcncodecs4.dll")
print plugin.load()           # result is false, why?
print plugin.errorString()  # application crashed at this time!

What should i do?
Thanks!

(PyQt: PyQt-Py2.5-gpl-4.3.1-1.exe,  Qt: qt-win-opensource-4.3.1-mingw.exe)