APEX

Hi,

I am using Application Express 4, wherein my requirement is as follows:
a)perform a redirect to a url using pl/sql procedure 'authenticate' when page loads
as follows:
return_to_uri varchar2(2000) := 'http://mysite.com:<port_no>/apex/<my_schema>.<package_name>.<procedure_name>';
openid_uri varchar2(100) := 'https://www.google.com/accounts/o8/id';
build_uri := '?ns=http://something.com'
|| '&id2=http://something2.com'
|| '&id3=http://something3.com'
|| '&return_to='|| urlencode(return_to_uri);
v_redirect_url := openid_uri || build_uri;
owa_util.redirect_url(v_redirect_url);

The above procedure performs a url redirect successfully to google page and sends back certain parameters appended to
return_to_uri' as follows 'http://mysite.com:<port_no>/apex/<my_schema>.<package_name>.<procedure_name>?ns=http://something.com&param_id=AQRST1299STR4&param_id2=1QPL86GBN4JK55F';

However, It always gives me BAD URL error.

I am receiving the params individually as follows in the procedure:

procedure get_redirect(p1 in varchar2,p2 in varchar2,p3 in varchar2)
begin
<redirect here again to a valid apex app>
end;

I have granted execute permission on APEX_PUBLIC_USER and PUBLIC to the procedure.
I am not sure if something like this is possible. Is it the '&' signs in the url that is causing a problem. I have tried searching for this but I am still not able to get any useful resource.
Any help would be greatly appreciated.
Thanks