You might be searching for the answer to the following error:
“Error: could not find an RSS or ATOM feed at that URL.”

After googled it out, and went to WordPress support forum (some of them even left unanswered), I found the following solution. i did and it solved my problem.

This solution worked for me when I was getting the same error. It can be found on this thread: http://wordpress.org/support/topic/120458/page/2?replies=24

The instructions I followed were:

1. Download the latest magpieRSS package from here: http://magpierss.sourceforge.net

There’s a lot of files in this tarred and gzipped archive. You only need the four .inc files in the root directory.

2. Dump rss_utils.inc, rss_parse.inc, and rss_cache.inc into the wp-includes directory.

3. Near the beginning of rss_fetch.inc, change the call to Snoopy.class.inc to this:

require_once( MAGPIE_DIR . ‘class-snoopy.php’);

This will work as class-snoopy.php is already in the wp-includes directory and there’s no need to install the extlib directory.

4. Rename rss_fetch.inc to rss.php and overwrite existing rss.php file in wp-includes with the new file