my link can't connect to controller..

[eluser]wasis[/eluser]
this is my link..

<li><a href="&lt;?=site_url().'?id_submenu='.$row-&gt;id_submenu;?&gt;/index.php/studio">
&lt;?php echo $row->nama_submenu?&gt;</a></li>

when i click the link, the result is..

404 Page Not Found
The page you requested was not found.

what is wrong with my script?