Building of MySQL plugin fails

I'm not able to install the MySQL plugin for Qt 4.1.0, because the nmake command does not find the file "stddef.h" located in the include directory of Microsoft Visual Studio .NET 2003. I get the following error message:

c:\Qt\4.1.0\include\QtCore\../../src\corelib\global\qglobal.h(25) : fatal error C1083: Cannot open include file: 'stddef.h': No such file or
directory

I am using the following commands

cd %QTDIR%\src\plugins\sqldrivers\mysql
qmake -o Makefile "INCLUDEPATH+=C:\Program Files\MySQL\MySQL Server 5.0\include" "LIBS+=C:\Program Files\MySQL\MySQL Server 5.0\lib\opt\LIBMYSQL.LIB" mysql.pro
nmake

Why does the nmake command fail?

are you sure that path to needed file available in environment variables INCLUDE?

Run <VisualStudio install dir>\VC98\Bin\VCVARS32.BAT to setup your environment correctly or use the Visual Studio shell to start the Qt build process.

See also:
Installing Qt - "windows.h" file
Installation error
Qt install issue on XP
How to set environment variables for all sessions when installing Qt
...