in the WA_Universal_Email/Email_Templates/registration.php file, change line 15:
<?php echo($WAGLOBAL_Root_URL); ?>users_confirm.php?ID=<?php echo($row_WAATKusers['UserID']); ?>&code=<?php echo($row_WAATKusers['UserVerificationCode']); ?>
to:
<?php echo($WAGLOBAL_Root_URL); ?>users_confirm.php?ID=<?php echo($_SESSION["UserID"]); ?>&code=<?php echo($_SESSION["randomConfirm"]); ?>