Modifying PATH environment variable Windows 7 doesn't work?

For almost a week, I had trouble adding a directory to PATH environment variable in Windows 7 64bit. I was trying to add a path of "C:\Program Files (x86)\gs\gs9.05\bin" to the PATH environment variable, but it just didn't work. I even restarted the PC although it should be unnecessary, opened the command prompt and checked the content of the PATH, but I couldn't find anything wrong. Until finally... found the culprit.. It is the whitespace.

If you add a path, just make sure not to put any whitespace between the semicolon. As an example, the following second path may not work because there is a whitespace between the semicolon ';' and the letter 'C' :

C:\Program files\program 1\bin; C:\Program files\program 2\bin;

To make it work, remove the whitespace between semicolon ';' and the letter 'C':

C:\Program files\program 1\bin;C:\Program files\program 2\bin;

That's all :)