force_download + CI 1.6.0

[eluser]javigarrido[/eluser]
Hi, my problem is a diffrent one:

the function force_download simply doesn't make any output.

$this->load->helper('download');
$data = file_get_contents("modulos/".$filename); // Read the file's contents
force_download($filename, $data);
echo $data."/".$filename;

Here i just get a white screen, but the file content are show (well you now, the strange codified content
I think it is simple enought, i just want the file downloaded with no other efect, ami doing something wrong?