日付を比較するプログラムを作成したのですが、なぜか上手く日付が
表示されません。ソースは↓ですが、おかしい箇所があれば、ご指摘下さい。

$date_set01="2006,06,10,00,00,00";
$date_set02="2006,06,12,23,00,00";
$set1=split(",",$date_set01);
$set2=split(",",$date_set02);

$d1 = mktime ($set1[3], $set1[4] , $set1[5] , $set1[1], $set1[2], $set1[0]);
$d2 = mktime ($set2[3], $set2[4] , $set2[5] , $set2[1], $set2[2], $set2[0]);
$time_diff = $d2 - $d1;

echo("時差:<br>");
echo date("Y",$time_diff) - 1970;
echo("年");
echo date("m",$time_diff) - 1;
echo("ヶ月");
echo date("d",$time_diff) -1;
echo("日");
echo date("H",$time_diff);
echo("時");
echo date("i",$time_diff);
echo("分");
echo date("s",$time_diff);
echo("秒");