[Plugin: Google XML Sitemaps] can't generate a sitemap

get a not found error on my sitemap url http://www.sinocism.com/sitemap.xml

and when i run xml sitemap generator debug function i get this message:
Warning: is_writable() [function.is-writable]: open_basedir restriction in effect. File(/) is not within the allowed path(s): (/nfs:/tmp:/usr/local:/etc/apache2/gs-bin) in /nfs/c09/h02/mnt/130028/domains/sinocism.com/html/wp-content/plugins/google-sitemap-generator/sitemap-core.php on line 1548

Warning: is_writable() [function.is-writable]: open_basedir restriction in effect. File(/) is not within the allowed path(s): (/nfs:/tmp:/usr/local:/etc/apache2/gs-bin) in /nfs/c09/h02/mnt/130028/domains/sinocism.com/html/wp-content/plugins/google-sitemap-generator/sitemap-core.php on line 1548

What can I do? Thanks

http://wordpress.org/extend/plugins/google-sitemap-generator/