Mail attach question

[eluser]Unknown[/eluser]
Hi, I have tried CI since yesterday and i make a view with a contact form (with the form helper)and it have a file input to attach a file to the mail, and it call a controller with the send mail commands. The mail is ok and come with the attach file, but when i see as attach in an email client the attach file have the temp name and not the real filename.
This is how i call the attach;

Code:

$varname = $_FILES['archivo']['name'];
$vartemp = $_FILES['archivo']['tmp_name'];
$this->email->attach($vartemp,$varname);

If i call Attach whith the $varname as firtsparameter the send mail class is unable to locate the file to attach.

Thanks in advance, sorry about the wrong english writing i am trying to learn this. Regards from Argentina.