Theme Test Drive Fatal Error Message WP 3.3.1

Hi,

I’m trying to use Theme Test Drive with Weaver Pro. It says:

“Fatal error: Call to undefined function wp_get_themes() in …/themedrive.php on line 262”

I tried the suggestions at http://wordpress.org/support/topic/plugin-theme-test-drive-error-message-on-wp-332, and it still didn’t work. the code was correct according to the page with the red and green lines. All I had to do was change the “theme_data” code as suggested on this page, and I’m still getting the error message.

I’m trying to change themes before updating to the latest WP version.

Thanks.