HI,
For a guest user, in community portal, page is not redirecting to next page. These are custom pages for which I have custom controllers. In salesforce pages are redirecting well and functionality is working fine. But in portal, on button click the same page is reloaded without any action.
below is th ecode I am using ot redirect to next page,
pageReference pageref = new pageReference(siteUrl+sitePrefix+'/Custom_Page'+'?param='+id);

what might be the reason? 

Regards,
Krishna