Post values from a function buildselect to another page

I have a function buildselect which gets the values of fields from a table, and displays the data in drop down menus which works fine. What I want to do, is get the value that the user chooses from each of the menus and post them to the next page where they are used as sessions. I'm not getting any errors, and which ever way I try, the values don't get posted across. Any ideas would be appreciated, thanks. The following is my code:

<?PHP
session_start();
require("connect.php");
                                            
  function buildSelect( $field_name, $curValue, $qry ) {
          $fldT  = "<select field_name='$field'>\n";
          $rs = @mysql_query( $qry );
          if ( $rs )
               while ( $rw = @mysql_fetch_array( $rs, MYSQL_NUM ) ) {
                    $val = $rw[0];
                    $sel = ( $val == $curValue ) ? " selected='selected' " : "";
                    $fldT .= "<option value=".$val." $sel>$val</option>\n";
               }

          $fldT .= "</select>\n";

          return $fldT;
     }        
$client = ( isset($_POST['client']) ) ? $_POST['client'] : "" ;
$name = ( isset($_POST['name']) ) ? $_POST['name'] : "$name" ;

$query  = "SELECT * FROM clients ORDER BY 'clients' LIMIT $offset, $rowsPerPage";
?>

<? echo buildSelect("client", $_POST['client'], "select client from Clients order by client"); ?>
<? echo buildSelect("name" , $_POST['name'], "select Name from Clients order by Name"); ?>
<? echo buildSelect("address" , $_POST['address'], "select Address from Clients order by Address"); ?>

On page 2, I simply have:

<?php
session_start();

$_SESSION['site'] = $_POST['site'];
$_SESSION['client'] =  $_POST['client'];
$_SESSION['campaign'] = $_POST['campaign']
etc ....
?>