Paths defined by R3RUNDIR or R3PROJECTDIR environment variables are not correct. Correspondingly, the compiler doesn't find the header files or link libraries of the SDK. Make sure the paths defined in the setup script are correct.

The shell (or CMD.EXE) cannot find the make or some other compiler specific programs. Make sure you have C/C++ compiler installed. The Path environment variable should contain paths to appropriate compiler folders so that compiler specific programs, such as make, can be found. Note for MS Visual C++ users: MSVC creates a bat file vcvars32.bat or vcvarsall.bat, which sets the necessary environment variables for using MSVC from CMD window. If you have installed MSVC, you should find this file somewhere from your hard drive.

Execution of setup script failed. This problem can show up on Windows 95/98/Millenium systems where the default environment size is too small and the environment variables run out of environment space. Use the 'System' menu of the cmd window to increase the size of the buffer reserved for the environment variables. Note: Windows 95 based flavours are no longer supported.

SDK was installed on a folder which contains white spaces. This problem only shows up on Windows platforms. Although white spaces, or longer file names in general, are nowdays supported by Windows operating systems, Windows is still not quite capable to handle them properly. Make sure you have unzipped the SDK to a folder whose name doesn't contain any white spaces. For example, c:\program files\v4sdk will not work because the 'program files' contain a white space. However, c:\v4sdk works just fine.

If you use C++ (your source file is named .cpp or .cc), make sure you use 'C' calling convention. C++ and C use different function decoration and you must use extern "C" directive to tell your compiler that you call 'C' function rather than C++.

Make sure you link appropriate r3 link libraries.