i m using htaccess to forbid all the request except one site (mysite.com)...

Request orderd from www.mysite.com to www.abc.mysite.com..

and i m using the following code but it does't allow www.mysite.com and gives internal server error

PHP Code:
<Directory "/download">
Order Deny,Allow
Deny from all
Allow from mysite
i have places this .htaccess on www.abc.mysite.com

can any body help me in this regard, that how can i stop access from other site and only allow mysite.com to abc.mysite.com??