I experienced a "blank page" too but I got it working now. I'm not sure which step fixed the problem but I'll tell you everything I did.
First I didn't check if RSS in ACP was on, sure enough, it was off. I turned it on and still no go. i went to
http://------.com/forum/external.php, still blank. I went into "external data provier" and just turn everything on, then rebuilt style, reload cv_rss_feeds.php and no more blank page.