Warning: Keyword density is 0%
There are a few ways you would see the warning message 'Keyword density is 0%' or 'The keyword was found 0 times'.
Keyword is Actually Missing
The keyword must match the entered keyword so "Keyword" does not match "Keywrod" or "MyKeywordAgain". Capitalization does not impact recognition in the current version.
Keyword Entered Outside of Content
There has been a recent increase in users with a plugin or theme that provides a visual page or content builder. This may not be compatible with our page analysis.
Foreign Language Keywords
Some non-latin, non-ideograph based languages may not calculate accurately. Please submit a bug through the appropriate channel.
Sometimes our plugin conflicts with another plugin, a feature within your theme or, in rare cases, something on your server. The fastest way to rule out conflicts is to deactivate all non-Yoast plugins and switch to a standard theme like Twenty Fourteen. If this resolves the issue, you have a conflict and should activate one plugin at a time until you locate the conflict. Finally after all plugins are active, switch to your theme. This will narrow down the conflict to a specific plugin or a theme conflict.