Help... I don´t know where is the error (very simple, i think!)

Help... I don´t know where is the error (very simple, i think!)

Dear friends.
 
I´m speaking from Brazil, and I´m trying click in a ckeckbox and a text appear into a textarea using php getting the data from mysql, but I don´t know where the error is.
 
Here is the code.
 
  1. <script type="text/javascript" src="jquery-1.4.1.min.js"></script>
     <script type="text/javascript">
     
       $(document).ready(function(){
          $("select[name=msgs]").change(function(){      
            $.post("texto_msgs.php",
             {msgs:$("#msgs option:selected").text()},
             function(valor){
                $("textarea[name=texto]").val(valor);
             }
             )
       










  2.       })
       })
     
     </script>


  3. <select name="msgs" id="msgs" size="8"><?php   
      require_once("conecta_sgv.php");
            $sql="SELECT * from mensagens WHERE destinatario = '$nome'";
            $qr=mysql_query($sql) or die (mysql_error());       
            while($ln=mysql_fetch_assoc($qr)){
              echo '<option value="'.$ln['id'].'">'.$ln['titulo'].' - De:'.$ln['autor'].'</option>';
            }
      ?>
            </select>







  4. <textarea name="texto" id="texto" rows="10" cols="65"></textarea>
    5. and the texto_msgs.php
          <?
      require_once("conecta_sgv.php");
      $id=$_POST['msgs'];
      $sql="SELECT * FROM mensagens WHERE id = '$id'";
      $qr=mysql_query($sql) or die (mysql_error());
     
      while($ln = mysql_fetch_assoc($qr)) {
       
        echo $ln['mensagem'];
     
      }  
      










    ?>
      anyone can please give me a light! Thanks and regards