424297 Fix Wordpress Plugin

Hi All, I had a wordpress plugin developed which automatically masked any external link so it looked like: [login to view URL] [login to view URL] etc... I recently upgraded wordpress to version 3.0 and this plugin no longer works, the masking appears to still be there but when I click any link I get the following error: Fatal error: Call to undefined function: is_multisite() in /var/www/vhosts/[login to view URL] on line 505 For info line 505 of [login to view URL] says: if ( is_multisite() ) { $this->charset = 'utf8'; if ( defined( 'DB_COLLATE' ) && DB_COLLATE ) $this->collate = DB_COLLATE; The redirect script is only one file so im sure someone who knows what they are doing will get this working again for me in no time. There is an admin are where you can set dmains not to be redirected / masked, this functionality needs to remain intact. I'm sure you will have further questions, get in touch. Cheers Paul