Error Code

I’m using the theme MaxiNews and trying to save a form, and when I do this is the error that I get, and I’m not sure what to do about it.

Warning:

unlink(/var/www/vhost/dev.signaturekitchensandbaths.com/app/webroot/wp/wp-content/themes/MaxiNews/cache/) [function.unlink]: Is a directory in /var/www/vhost/dev.signaturekitchensandbaths.com/app/webroot/wp/wp-content/themes/MaxiNews/functions.php on line 1963
1

http://ww.wp.xz.cn/plugins/visual-form-builder/