RSS Feed and Search broken after install.

When I try to enter anything into the wordpress search box I get:
Plugin: WordPress SEO by Yoast



Fatal error: Call to undefined function is_post_type_archive() in wp-content\plugins\wordpress-seo\frontend\class-frontend.php on line 474

rss feed is displaying a php error:
<b>Fatal error</b>: Call to undefined function is_post_type_archive() in <b>wp-content\plugins\wordpress-seo\frontend\class-frontend.php</b> on line <b>191</b>

I'm running the latest version of plugin. How can this be fixed?