RSS Warning?

This is the warning message I’m getting:

Warning: copy(/home2/myecashs/public_html/blog/wp-content/plugins/fix-rss-feed/bak/wp-blog-header.php) [function.copy]: failed to open stream: Permission denied in /home2/myecashs/public_html/blog/wp-content/plugins/fix-rss-feed/fix-rss-feed.php on line 169
/home2/myecashs/public_html/blog/wp-content/plugins/fix-rss-feed/bak/wp-blog-header.php can not be overwrited, please check file permission
Error, /home2/myecashs/public_html/blog/wp-blog-header.php can not be writed, you must set writable permission to /home2/myecashs/public_html/blog/wp-blog-header.php file, otherwise will no success!