[Plugin: Sphider for WordPress] Database Errors and Warnings

I recently installed Sphider and I got it working briefly but now I’m getting 2 errors every time I try to search something. This is the error message I get:

Warning: require_once(/raid/wp-blog-header.php) [function.require-once]: failed to open stream: No such file or directory in /raid/www/webroot/your-website/wp-content/plugins/sphider/settings/database.php on line 9

Fatal error: require_once() [function.require]: Failed opening required ‘/raid/wp-blog-header.php’ (include_path=’.:/www/php-includes’) in /raid/www/webroot/your-website/wp-content/plugins/sphider/settings/database.php on line 9

and line 9 refers to something in wp-blog-header.php but I’m not sure what. Any ideas where this can be corrected? Here’s the code from that line:

require_once(realpath($wp_root_path.’/wp-blog-header.php’));