Show quantity of posts in last 24hours inside a particular category [Wordpress]

I been through this wordpress plugin http://wordpress.org/extend/plugins/count-posts/ to show quantity of posts in last 24hours inside a particular category which may be proven any place in web site by using this fundtion

<?php echo count_posts('Uncategorized', '1', true); ?>

But there's only exhibiting quantity of all posts inside a particular category, neglecting last 24hours.. Help, this is actually the code from the wordpress plugin

<?php
/*
Plugin Name: Count Posts
Plugin URI: http://code.andrewhamilton.net/wordpress/plugins/count-posts
Description: A simple plugin that provides a template function to count posts, as well as filtering by category and over time in days. The function can either return or display the result. <em>Based off Clint Howarth's count_posts</em>
Author: Andrew Hamilton
Version: 1.0
Author URI: http://andrewhamilton.net/
Licensed under the The GNU General Public License 2.0 (GPL) http://www.gnu.org/licenses/gpl.html
*/

//---------------------------------------------------------------------------
//  Setup Default Settings
//---------------------------------------------------------------------------

//Detect WordPress version to add compatibility with 2.3 or higher
$wpversion_full = get_bloginfo('version');
$wpversion = preg_replace('/([0-9].[0-9])(.*)/', '$1', $wpversion_full); //Boil down version number to X.X

//----------------------------------------------------------------------------
//      MAIN FUNCTION
//----------------------------------------------------------------------------

function count_posts ($category = '', $daysago = '0', $display = true)
{
    global $wpversion, $wpdb;

    $now = current_time('mysql');

    // Get the date from $daysago
    if ($span != 0) {
        $then = gmdate('Y-m-d H:i:s',(time() + (get_option('gmt_offset') * 3600) -($daysago * 86400)));
    }

    // Get the category ID from category name
    if (!empty($category) && $wpversion < 2.5)
    {
        $catid = $wpdb->get_var("SELECT cat_id FROM $wpdb->categories WHERE cat_name = '$category' ");
    }
    elseif (!empty($category) && $wpversion >= 2.5)
    {
        $catid = $wpdb->get_var("SELECT term_id FROM $wpdb->terms WHERE name = '$category' ");
    }

    // Construct Query
    $query = "SELECT COUNT(*) FROM $wpdb->posts ";

    if (!empty($category) && $wpversion < 2.5) 
    {
        $query .= "LEFT JOIN $wpdb->post2cat ON($wpdb->posts.ID = $wpdb->post2cat.post_id) ";
    }
    elseif (!empty($category) && $wpversion >= 2.5)
    {
        $query .= "LEFT JOIN $wpdb->term_relationships ON($wpdb->posts.ID = $wpdb->term_relationships.object_id) ";
    }

    $query .= "WHERE (post_date <= '$now') ";

    if (!empty($category) && $wpversion < 2.5) 
    {
        $query .= "AND (category_id = $catid) ";
    }
    elseif (!empty($category) && $wpversion >= 2.5)
    {
        $query .= "AND (term_taxonomy_id = $catid) ";
    }

    if ($span != 0) {
        $query .= "AND (post_date >= '$then') ";
    }

    $query .= "AND (post_status = 'publish') ";

    //Output
    $output = $wpdb->get_var($query);

    if ($display) 
    {
        echo $output;
    }
    else
    {
        return $output;
    }

}
?>