iframe new window, popup getting blocked by popup blocker

Need this fix fast. We have iframed a script with a form that we have opened in new window as below (line 4). However, the popup is being blocked by popup blockers on browsers. Need someone to provide a code fix so that popup blocker WONT block the new window. <form action="" method="get" target="_blank" style="display: inline" name="fdPaypal"> <input type="hidden" name="business" value="" /> <input type="hidden" name="item_name" value="" /> <input type="hidden" name="invoice" value="" /> <input type="hidden" name="amount" value="" /> <input type="hidden" name="currency_code" value="" /> <input type="hidden" name="return" value="" /> <input type="hidden" name="notify_url" value="[login to view URL]" />