Need Help whith DOBBLE SELECT

function sub_select($sub_id){
$menu_sel="";
$db=$GLOBALS[db];
### SECOND QUERY
$db->Query("SELECT * FROM $GLOBALS[menu_DB] where typ='2' and sub_id='$sub_id' order by id");
for ($num = 0; $num < $db->RowCount(); $num++) {
$sub_row = $db->Row($num);
$menu_sel.="<option value=\"$sub_row->id\"> - $sub_row->name</option>";
}
return $menu_sel;
}

$menu_sel="<select size=\"1"\ name=\"New_Menu\">";
### FIRST QUERY
$db->Query("SELECT * FROM $menu_DB where typ='1' and lang='$lng' order by id");
$num_max=$db->RowCount();
for ($index = 0; $index < $num_max; $index++) {
$row = $db->Row($index);
$menu_sel.="<option value=\"$row->id\" $sel_lisa>$index $row->name $row->id</option>";
$menu_sel.= sub_select($row->id);
}
$menu_sel.="</select>";


echo $menu_sel;

If i call sub_select($row->id);, first Query is going to null!!!

Result mast be select menu:

Menu 1
- SUB MENU
- SUB MENU
- SUB MENU
Menu 2
- SUB MENU
Menu 3
Menu 4

Bat I loss all data in Second query;