Facebook API: redirect_uri

I've readeded that FB API have problems with redirect_uri - and i've try to make it work on my framework. Problem is easy, but i haven't found working solution so i think this is right place, and someone help me.

I've creating login link:

$loginUrl = $helper->getLoginUrl( $app_url . 'fb/oauth/' , $permissions );

where $app_url . 'fb/oauth/' looks like this http://domain.com/fb/oauth/

This path is redirected thru htaccess > index.php (routing) > plugins/facebook/oauth.php

And in oauth.php file i've valid code - but i've get error:

Error validating verification code. Please make sure your redirect_uri is identical to the one you used in the OAuth dialog request

Main problem is that i don't want to redirect to domain.com/fb_oauth.php - i prefer to use rewrite/route way to be more pretty. Every think is correct, i've checked slash at the end (because some have problems with that).

I also think that error may be in the way that route redirect to callback file:

if($route->path = 'fb/oauth') {
    include $app_path . "plugins/Facebook/facebook-callback.php";
} else {
    die("Unknown");
}

Please help me - i don't have other ideas. I prefer to not use direct link to .php, and use my way (my variables are defined before include destination file)

Thank You !