Update line 273 of the securityassisst Helper_PHP.php file to:
$fullReturnURL = WA_SecurityAssist_rel2Abs($WA_Auth_Parameter["returnURL"]) . ((strpos($WA_Auth_Parameter["returnURL"],"?")!==false)?"&":"?") . "fp_id=" . rawurlencode($row_WA_Auth_RS[$WA_Auth_Parameter["keyColumn"]]) . "&fp_email=" . rawurlencode($row_WA_Auth_RS[$WA_Auth_Parameter["toAddressColumn"]]) . "&fp_data=" . rawurlencode($dataStr);