supplied argument is not a valid stream resource???

<?php
error_reporting(E_ALL);
$file = 'textak.body';
if (isset($_GET['action']) AND $_GET['action'] = 'send')
{
$text = fopen ($file, "r");

    if (fwrite($file, $content) === FALSE) {
        echo "Cannot write to file ($file)";
        exit;
    }

    fclose($file);
}
echo '<form action="edit.php?action=send" method="post">';
echo '<textarea name="content" cols="60" rows="20">'.file_get_contents($file).'</textarea><br />';
echo '<input type="submit" value="ulož">';
echo '</form>';
?>