内部服务器错误，当我试图访问管理员url(主页正在工作)

我正在处理。htaccess文件，前端工作正常。但是当我试图访问管理它给我内部服务器错误。它是一个自定义mvc框架。

这是我的。haccess文件

DirectoryIndex index.php
Options -Indexes
Options +FollowSymlinks
Options -MultiViews
ErrorDocument 404 /sitemap.php
RewriteEngine on
RewriteBase /
RewriteCond %{HTTP_HOST} ^vividtron.demolocation.com [NC]
RewriteRule ^index.htm$ /index.php [NC]
RewriteRule ^all-category.htm$ /all-category.php [NC]
RewriteRule ^brands.htm$ /brands.php [NC]
RewriteRule ^search.htm$ /search.php [NC]
RewriteRule ^([_-a-zA-Z0-9]+)$ /sub-category.php?furl=$1 [NC]
RewriteRule ^customer-service.htm$ /customer-service.php [NC]
RewriteRule ^([_-a-zA-Z0-9]+).htm$    /static-page.php?furl=$1 [NC] 
RewriteRule ^offer/([_-a-zA-Z0-9]+).htm$    /special-offer.php?furl=$1 [NC]
RewriteRule ^pages/([_-a-zA-Z0-9]+).htm$    /popup-pages.php?furl=$1 [NC]
#RewriteRule ^category/([_-a-zA-Z0-9]+)$ /product-listing.php?surl=$1 [NC]
RewriteRule ^category/([_-a-zA-Z0-9]+)$ /featured-product.php?surl=$1 [NC]
RewriteRule ^brand/([_-a-zA-Z0-9]+)$ /product-series.php?burl=$1 [NC]
RewriteRule ^series/([_-a-zA-Z0-9]+)/([_-a-zA-Z0-9]+)$ /model-listing.php?burl=$1&surl=$2 [NC]
RewriteRule ^product/([a-zA-Z0-9_-]+)$ /product-detail.php?furl=$1 [NC]
RewriteRule ^([._-a-zA-Z0-9]+)/([_-a-zA-Z0-9]+)/([_-a-zA-Z0-9]+)$ /pro-detail.php?url=$1&proId=$2&bid=$3 [NC]
RewriteRule ^([._-a-zA-Z0-9]+)/([_-a-zA-Z0-9]+)$ /pro-detail.php?url=$1&proId=$2 [NC]

谢谢预付。请查看文件为什么url http://vividtron.demolocation.com/admin/login.php不工作