Enviroment Variables in VS2010 and XP

Hi,

I created a enviroment variable to manipulate the path of my .h files.
I added the variable in Additional Include Directories in the properties of project.

My notebook have XP and when i compile, a error of don’t open the .h file occurs.

But, i tried in another machine with windows 7 and works fine.

What can i do to solve that?

Thanks,