Drupal_add_css drupal_add_js not working dynamically

I am working on a drupal-7 project that have many CSS/JS files that need to be added dynamically. This is the code which i am using in mymodule_init()

function doLookup($baseRootDir)
    {
    if (variable_get('xmldata')) {
        $xmldata = variable_get('xmldata');
    } else {
        $xmldata = '';
    }
    $rootDir = realpath($baseRootDir . DIRECTORY_SEPARATOR . $xmldata);
    $di = new RecursiveDirectoryIterator($rootDir);
    foreach (new RecursiveIteratorIterator($di) as $filename => $file) {
        $fileInfo = new SplFileInfo($filename);
        if (strtolower($fileInfo->getExtension()) == "css") {
            // Include this CSS file in drupal
            drupal_add_css($cssFileName, array('type' => "file", 'group' => CSS_DEFAULT, 'every_page' => TRUE));
        } elseif (strtolower($fileInfo->getExtension()) == "js") {
            // Include this JS file in drupal
        }
    }
}

I am calling this function in hook_init() which doesn't seem to be working. I have tried clearing drupal cache as well.
Please help me out i need to complete this asap :(