Erros em script de banner

Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource in /var/www/verBanner.php on line 4

Warning: Cannot modify header information - headers already sent by (output started at /var/www/verBanner.php:4) in /var/www/testing/nitbusca/verBanner.php on line 8

exibirBanner.php

<?phpinclude "conexao.php";// capturar banner$query = "SELECT codigo, foto, alt, hits FROM banner WHERE ativo='1' ORDER BY hits LIMIT 1";list ($banner_codigo, $banner_foto, $banner_alt, $banner_hits) = mysql_fetch_array(mysql_query($query,$con));$banner_hits++;// atualizar hits do banner$update = "UPDATE banner SET hits=$banner_hits WHERE codigo=$banner_codigo";mysql_query($update,$con);echo "<a href='verBanner.php?codigo=$banner_codigo' alt='$banner_alt'><img src='./img/banners/$banner_foto' border=0></a>";?>

verBanner.php

<?phpinclude "conexao.php";$query = "SELECT clicks, url FROM banner WHERE codigo=$codigo";list ($clicks, $url) = mysql_fetch_array(mysql_query($query,$con));$clicks++;$update = "UPDATE banner SET clicks=$clicks WHERE codigo=$codigo";mysql_query($update,$con);header("Location: $url");?>