Jime,
If you are working under WinNT/Win2000 then settings are valid only within current DOS session.
You can also try WinAPI way:

Declare Long ExpandEnvironmentStrings in Win32API String, String, Long
src = "%TESTING%"
res = SPACE(256)
ln = ExpandEnvironmentStrings(src, @res, 256)
res = Left(res, ln)
?res

>When I test the GETENV(), I can only get some environments. And if I use SET TESTING=1 in DOS prompt, the run getenv("TESTING"), there's just no return. May I ask why?