Since WordPress 2.3, WordPress Dashboard provides an Incoming Links widget that ables to display backlinks that have been received by the blog, i.e. inbound links that point from external blogs and bring link juice (aka Google PageRank) to the linked blog. WordPress has been using Google Blog Search as the search engine to provide such information on incoming links.
The Incoming Links widget box on WordPress Dashboard allows blogger to customize and configure the number of inbound links items that user want to display in the Dashboard. However, with the default configuration of Google Blog Search Incoming Links RSS feed URL, it’s impossible to increase the number of incoming links displayed (cannot make the number of incoming links displayed to more than 10 (ten)).
The cause for the WordPress Incoming Links widget maximum number of items error is because the default Google Blog Search RSS feed limits the maximum backlinks returned by Google to 10. And WordPress does not cache the older incoming links that have previously been received by it, making the Dashboard only has a maximum of 10 inbound links to display at any time.
To fix problem cannot or unable to increase number of incoming links displayed on WordPress Dashboard, just increase the number of back links returned by Google Blog Search RSS feed. To do so, hover the mouse over the Incoming Links widget pane, and click on Configure that appears. Edit the existing RSS feed URL to change the number of items from 10 to 20, or any number you like. However, value greater than 20 is not meaningful as widget can only display maximum of 20 incoming links.
For example, the modification has to be done to the num parameter, which is bold.
Adjust also the value of number of items you would like to display from the pull down list. Click Submit when done. Voice, now more than 10 incoming links can be shown on Dashboard.