[Plugin: NextScripts: Social Networks Auto-Poster] Facebook Conditional Thumbnail

Try using this:

<?php
  $src = '<?php bloginfo('template_directory'); ?>/images/default-category-image.jpg" alt="<?php the_title(); ?>'
      if (is_category('XXXX')) {
      the_post_thumbnail('thumbnail', array('$src'));
}
?>

Thanks for your answer but unfortunately it doesn’t help me.
I got this code in header which work great in Facebook developers debug, share, like, etc…but not with this plugin cause he always grab the featured image thumbnail not the og:image?

<?php if ( in_category( 'x' )) { ?>
					<meta property="og:image" content="<?php $post_thumbnail = bloginfo('template_directory') . '/images/x.png'; echo $post_thumbnail; ?>" />
                    <link rel="image_src" href="<?php $post_thumbnail = bloginfo('template_directory') . '/images/x.png'; echo $post_thumbnail; ?>" / >
				<?php } else { ?>
            <meta property="og:image" content="<?php $post_thumbnail = wp_get_attachment_image_src(get_post_thumbnail_id($post->ID),'large'); echo $post_thumbnail[0]; ?>" />
             <link rel="image_src" href="<?php $post_thumbnail = wp_get_attachment_image_src(get_post_thumbnail_id($post->ID),'large'); echo $post_thumbnail[0]; ?>" / >
            <?php } ?>

I believe the changes have to be done in how the plugin grabs the thumbnail and i tried it but again without success.
Help please.
Thanks