use query_posts get posts by multiple custom fields

Hi, I’ve hunted for an answer to this and haven’t found one that works. Trying to make sense of someone-else’s code. I’m trying to show posts by author ID, post type=private, and two custom fields ‘paid_user’ and ‘txrole’. The code below is just returning all private posts from all users, and not differentiating between the custom fields. What am I doing wrong? Thank you for your help.

<?php

	global $wp_query;
	$query_vars = $wp_query->query_vars;
	$post_per_page = 20; 

	global $current_user;
	get_currentuserinfo();
	$uid = $current_user->ID;

	$winner = array(
	'meta_key' => 'winner',
	'value' => $uid,
	'compare' => '='
	);

	$paid = array(
	'meta_key' => 'paid_user',
	'value' => "0",
	'compare' => '='
	); 

	$tx_role = array(
	'meta_key' => 'txrole',
	'value' => "bought",
	'compare' => '='
	); 

	$args = array(
	'post_status' => 'private',
	'post_author'=>$uid,
	'order' => 'DESC',
	'orderby' => 'date',
	'posts_per_page' => $post_per_page,
	'pages' => $query_vars['paged'],
	'meta_query' => array($winner, $paid, $tx_role));

	query_posts($args);

	if(have_posts()) :
		while(have_posts()) : the_post();
			get_backoffice();
		endwhile;

		if(function_exists('wp_pagenavi')): wp_pagenavi(); endif;
	else: _e("None",'AuctionTheme');

	endif;

	wp_reset_query();
?>

PS – get_backoffice() is just a function to format the results, which is working fine elsewhere.