Button is pressed but it dont jumps into the if

I googled it but everything I try does not work

Here the problem

 if ($po_status == "2"){
  print '<form method="POST" action="./base.php" name="base">';
  $tableRow .= "<td align='center' class='thStandardI' colspan='1'>";
  $tableRow .= "<input type='submit' value='Confirm' name='confirm' style='width: 160px;' class='thStandardT'>";
  print '</form>';
}


 if (isset($_POST['abschliessen']))     { 
  $aendern = "UPDATE po_header SET last_update = CURRENT_TIMESTAMP(), po_status = '3' WHERE po_id = ".$poid;
  $result=db_query(Array($aendern));
}

I tryed to use a form and without form, or only if ($_POST['confirm']) with a normal button not submit, and I also tryed to call a function onClick but the never jumps inside my second if where the update is.