We cannot find Windows.h

[admrialkunkka]

Our team has never used image processing before. We are using windriver and the code generated for us by the NI Vision assistant and the code for processing the axis camera image was exported as c so we changed it to c++. We then changed the import of the machine file to #include "nimachinevision.h"
but when we build the code we get, #include <windows.h>, windows.h: No such file or directory. Where can I find the windows.h file?