Apache 2.2.6 中alias的目录不能自动打开index.php文件，何故？

<VirtualHost *:80>
    Alias /mysql "/home/webapps/phpmyadmin"
    <Directory "/home/webapps/phpmyadmin">
        Options FollowSymLinks
        AllowOverride None
        Order allow,deny
        Allow from all
    </Directory>

    DocumentRoot "/usr/local/apache/htdocs"
    ServerName 127.0.0.1
    DirectoryIndex index.html index.php
    IndexOptions FancyIndexing VersionSort
</VirtualHost>

UP

AddType application/x-httpd-php .php ?