CodeIgniter with Thickbox

[eluser]Unknown[/eluser]
Hi guys i newbie using CI, and I have a question about the jQuery thickbox plugin.

I am trying to combine href link with thickbox, and I haved trouble in here.

Code:

<a id="example" class="thickbox" href="&lt;?= site_url('example/');?&gt;">example</a>

and for thickbox function it must add : ?keepThis=true&TB_iframe=true&height=250&width=400 in behind the href link, and cause of this I get error message : 404 Page Not Found.

my question :

1. What I must doing to fix this error ? please describe step by step about the solution
until fix it.

Please help me, It would be a great contribution