If the function succeeds, the return value is greater than 31.

If the function fails, the return value is one of the following error values:

Value Meaning
0 The system is out of memory or resources.
ERROR_BAD_FORMAT The .EXE file is invalid (non-Win32 .EXE or error in .EXE image).

ERROR_FILE_NOT_FOUND The specified file was not found.
ERROR_PATH_NOT_FOUND The specified path was not found.

MSDN上一大堆，成功返回值大于31，其他的返回值如上