Navie USB port drivers (Arduino Due mode)

Having trouble installing the "Arduino Due" USB driver for the Native USB Port for Windows XP Pro SP3, I edited the \arduino-1.5.1r2\drivers\Arduino Due.inf file as suggested :

[DeviceList]
%DESCRIPTION%=DriverInstall, USB\VID_2341&PID_003E&MI_00, USB\VID_2341&PID_003E

Windows XP now correctly installs the Arduino Due driver for the Native USB port.
But sketch "keyboarSerial" don't work.
I upload sketch (ok), open Serial Monitor, digit a letter (inCHAR) and press "send", no replay (inChar+1).
What is the problem?