其他php命令不能与htaccess文件一起使用

I wanted to run php code in html file so i added this code in htaccess file.

AddType application/x-httpd-php .html .htm

when i run below code with it. it works fine.

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
    <HEAD>
        <TITLE>Use PHP in HTML files</TITLE>
    </HEAD>

    <BODY>
        <h1>
            <?php 
                echo "It works!"; 
            ?>
        </h1>
    </BODY>
</HTML>

But when i include any file from my web directory then it doesn't work. i have used below code.

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
    <HEAD>
        <TITLE>Use PHP in HTML files</TITLE>
    </HEAD>

    <BODY>
        <h1>
            <?php
                include("file.php");
                echo "It works!"; 
            ?>
        </h1>
    </BODY>
</HTML>

What i should do to run php code in html.If this is not possible then what is another way to execute php code in html file?