Why wrong script works everytime?

[Rommeo]

My language-changing links was like this :

 

www.mysite.com/lang.php?lang=en

// lang.php script takes the value by get

// writes it to language cookie

// gives "language error" if get is empty or any other thing except "fr / en / de " and sets the cookie to default language.

//my index.php checks the cookie and uses the language in the cookie.

 

I changed it to and made a link from my index.php(template) to ;

www.mysite.com/l/en

RewriteRule ^l/([a-z-_]+)/?$ lang.php?lang=$1 [L]

 

that goes to :

www.mysite.com/lang.php?lang=en

 

it works well just when i click the "English" ( changing language) button.

 

but the problem is :

when I click the any other page (that all pages uses the template that I mentioned at the top) , it gives me "Language Error" and script sets cookie to default language so my clicking "en" does not work here. This is very interesting cause I guess, when ever I enter any page, everytime my .htaccess runs, it sends empty get value to my lang.script I guess and everytime it sets the cookie to default language, and I can not change the default language.. if it was working properly,while clicking any other page ( after clicking "en" ), the index.php ( template ) would read the cookie that is "en" and prints the layout as in the cookie (en), it would not run the lang.php everytime.

 

I dont know what can cause this,

Is there any solution for this ?