[php] Disable text input history

Possible Duplicate:
How do you disable browser Autocomplete on web form field / input tag?

I am building an application which will be accepting credit card data. I would like to make sure that the browser does not remember what has been typed into the text inputs for credit card number. I tried passing the following headers:

header("Expires: Tue, 03 Jul 2001 06:00:00 GMT");
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
header("Cache-Control: no-store, no-cache, must-revalidate, max-age=0");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");

Still, once the page reloads, I can click the credit card text input field and it will let me see what I wrote in it before. How can I prevent this?

<input type="text" autocomplete="off" />