Some time ago I noticed that WebTalkTo RSS feed information on my personal site - maximaginsky.com - wouldn't appear any more. Instead, for the last five WebTalkTo feed entrees, I could see an error message ;[ After a while I figured out the issue and oh boy! It was so crazy simple to fix.
How to fix RSS error generated by Wordpress
Remove extra space after the closing PHP tag of the theme functions file - functions.php
Before taking any actions validate your feed online using Feed Validation Service by W3C