GoDaddy主机上的连接响应（返回500内部服务器错误）

Localhost picture working when it comes in AJAX see the picture below

Localhost

But in LIVE it returns 500 internal server error

enter image description here

We're done by overriding the httpd.conf by .htaccess with

<ifModule mod_headers.c>
    Header set Connection keep-alive
</ifModule>

and by putting

header("Connection: keep-alive");

in db.php still the Connection: close still there.

We used PDO connection string. And last thing if the process used INSERT INTO statement it gives the error of 500 internal server error but in SELECT and UPDATE everything works fine. Can someone give an advice to fix this problem?