Query to get specific meta_values from specific meta_key and post category

Hi there!

I’m trying to get meta_values from specific meta_key and from specific post category.

Here’s the piece of code that I’m using:

$querystr = "
        SELECT wpostmeta.meta_value
        FROM $wpdb->postmeta wpostmeta

        LEFT JOIN $wpdb->posts wposts ON wpostmeta.post_id = wposts.ID
    	LEFT JOIN $wpdb->term_relationships ON (wpostmeta.post_id = $wpdb->term_relationships.object_id)
    	LEFT JOIN $wpdb->term_taxonomy ON ($wpdb->term_relationships.term_taxonomy_id = $wpdb->term_taxonomy.term_taxonomy_id)
        WHERE wpostmeta.meta_key = 'my_meta_key'
        AND $wpdb->term_taxonomy.taxonomy = 'category'
    	AND $wpdb->term_taxonomy.term_id IN (5408)
";

    $results = $wpdb->get_results($querystr, OBJECT);

With this code, I’m getting all values from $wpdb->postmeta, but not filtering by category? Are there something wrong with my query?

Any help will be apreciated ??