Apache simple redirect not working

I’m trying to redirect all requests from my website to a subdir but it doesn’t work. This thing is going to make me crazy and any help would be appreciate.

In conclusion, I want this :

• http://mywebsite/test or http://mywebsite/test42 or http://mywebsite/everything

to

• http://mywebmysite/mydir

Here is my rule :

RewriteEngine On

RewriteCond %{REQUEST_URI} !^/mydir/$

RewriteRule ^(.*)$ /mydir/

But it doesn’t work… Apache doesn’t redirect. What am I doing wrong??

Thank you,

Regards.