I try to add a currency update form in product_info display page, but after redirect, the URL back to dynamic, why?
the url for product page on my server is correct, even the form action url has not prblem.

which is :
before form submit:
http://temp.local/test-examples-c-23/test-120-p-84.html
form action url in view html mode:
http://temp.local/test-examples-c-23/test-120-p-84.html
after form submit
http://temp.local/index.php?main_pag...id=84&cPath=23

form code:

<?php echo zen_draw_form('currencies_form_header', zen_href_link(zen_get_info_page($products_id), 'cPath=' . $cPath . '&products_id=' . $products_id, $request_type), 'get');
echo zen_draw_hidden_field('main_page','product_info');
echo zen_draw_hidden_field('cPath',$cPath);
echo zen_draw_hidden_field('products_id',$'products_id);
echo zen_draw_pull_down_menu('currency', $currencies_array, $_SESSION['currency'], 'onchange="this.form.submit();"') . zen_hide_session_id().'</form>';
?>
after submited and the page reload as:

http://test.local/index.php?main_pag...d=18&cPath=1_2

where is the problem? i test ultimate seo 2.101 on another test site, that version is good.
which is :
before form submit:
http://temp.local/test-examples-c-23/test-120-p-84.html
after form submited
http://temp.local/test-examples-c-23/test-120-p-84.html