Post image error

Hello,
I am using plugin Post Image and when I enter this code:
$my_querytest = new WP_Query(‘showposts=4&cat=3,4,11’);
while ($my_querytest->have_posts()) : $my_querytest->the_post();
$do_not_duplicate = $post->ID;
post_image(‘http://www.admentour.cz/wp-content/uploads/test.png’);

There is error in my sidebar:
WordPress database error: [You have an error in your SQL syntax. Check the manual that corresponds to your MySQL server version for the right syntax to use near ‘) AND post_type = ‘attachment’ AND post_mime_type LIKE ‘%image%]
SELECT ID, post_parent, post_title, post_content, guid FROM wp_posts WHERE post_parent IN() AND post_type = ‘attachment’ AND post_mime_type LIKE ‘%image%’ ORDER BY post_date ASC

Please do you know somebody where can be problem?
Thank you very much…