Datbase error using WPEnclosures Plugin

I’ve installed the WP Enclosures Plugin without a hitch. The MySQL database was updated using the enclosed SQL file. However, when I write a new post (even without enclosures), I get this error:

Any ideas what I should do? Thanks!

[code]Database error: [Unknown column 'enclosure_url' in 'field list']
INSERT INTO wp1_posts (ID, post_author, post_date, post_date_gmt, post_content, post_title, post_excerpt, post_status, comment_status, ping_status, post_password, post_name, to_ping, post_modified, post_modified_gmt, enclosure_url, enclosure_type, enclosure_length) VALUES ('0', '1', '2005-02-10 11:36:55', '2005-02-10 02:06:55', '\"IThanks to the inclusion of highly selected affiliates, About Web Logs now has its very own online shop at CafePress. I\'ve got unique blogging gear for bloggers (and those who love \'em). --- T-shirts, mugs, mousepads, prints, sweatshirts and more. Great for gift-giving! 😉 Anyway, yep, I did the designs myself. And, I\'m hoping to add more designs in the future. If all goes well, that is. ', 'Blogging Gear', '', 'publish', 'open', 'open', '', 'blogging-gear', '', '2005-02-10 11:36:55', '2005-02-10 02:06:55', '', '', '')

Warning: Cannot modify header information - headers already sent by (output started at /home/shaicogg/www/www/wp-includes/wp-db.php:80) in /home/shaicogg/www/www/wp-admin/post.php on line 148[/code]