php页面cookie错误

Question

链接login1.php 出现如下告警信息：
Warning: Cannot modify header information - headers already sent by (output started at /var/www/ipgl/login1.php:2) in /var/www/ipgl/login1.php on line 87

Warning: Cannot modify header information - headers already sent by (output started at /var/www/ipgl/login1.php:2) in /var/www/ipgl/login1.php on line 88

Warning: Cannot modify header information - headers already sent by (output started at /var/www/ipgl/login1.php:2) in /var/www/ipgl/login1.php on line 89

Warning: Cannot modify header information - headers already sent by (output started at /var/www/ipgl/login1.php:2) in /var/www/ipgl/login1.php on line 90

Warning: Cannot modify header information - headers already sent by (output started at /var/www/ipgl/login1.php:2) in /var/www/ipgl/login1.php on line 91

lingin1.php的代码如下：
if($qx==0)
  {
    setcookie("yhmch","$yhmch";
    setcookie("jdmch","$jdmch";
    setcookie("qx","$qx";
    setcookie("dlqr","$dlqr";
    header("Location:index.php ";
  }
请问是何原因，在论坛里找了一圈，没有结果。

php.ini 中已经配置
session.auto_start = 1

谢谢！