Google Sitemap plugin not building sitemap…

I cannot make a sitemap file it says that the files may not be writable. I am positive that my root dir is writeable not to mention i even created the files and made those writeable and still getting an error. I used the debug featured and got this:

Notice: Undefined index: path in httpdocs/portfolio/wp-admin/includes/file.php on line 25

I checked that file and line and it has this:
$home_path = $home_path[‘path’];

I have NO idea how to debug this, someone please assist, thanks.