The active schema does not support the element 'element.'
An element appears in the HTML markup for your page that is not permitted by the HTML schema set in the targetSchema property of the page.
To respond to this message
Replace this unsupported element with HTML markup that is supported in the HTML version indicated in the targetSchema property for this Web page.
—or—
In the Properties window for this Web page, change the targetSchema property to a Web browser that supports the desired element.