Codeignither พอ select valur จาก json แล้วเอามาแสดงใน โดย appand ลงใน select option แล้วพอเรียก $this->input->post มันไม่มี value ค่ะ

     <div id="popup_login" align="left"  style="display:none">
            <p align="right"><a href="#"  class="close_login"><img src="<?=base_url()?>/assets/button/del_big.png" width="30"></a></p>
            <table width="500" border="0">
            <tr>
            <td width="50%" align="right"></td>
            <td width="70%"><input type="hidden" name="pProID" id="pProID" value="<?php echo $Max; ?>" readonly="true" /></td>
            </tr>
      
            <tr>
            <td width="50%" align="right">ชื่อสินค้า :</td>
            <td width="70%"><input name="pProName" type="text" id="pProName" /><span id="sProName"/></td>
            </tr>
      
            <tr>
            <td width="50%" align="right">รุ่น :</td>
            <td width="70%"><input name="pProModel" type="text" id="pProModel" /><span id="sModel"/></td>
            </tr>
             
            <tr>
            <td width="50%" align="right">ราคา :</td>
            <td width="70%"><input name="pProPrice" type="text" id="pProPrice" onkeydown=="checknum();" /><span id="sProPrice"/></td>
            </tr>
      
            <tr>
            <td width="50%" align="right">ประเภท :</td>
            <td width="70%" >
            
           <div id="TopMain">
            <br>หัวข้อหลัก : <select id="Selecttopmain" class="Selecttopmain" name="Selecttopmain" >
            <?php foreach ($rTopMain as $TMain){  
            ?>
                <option value="<?php echo $TMain["TopID"]; ?>"><?php echo $TMain["TopName"]; ?></option>
                <?php 
                }
                ?>
             </select> <span id="sTMain"/>     
            </div>
  
            <div style="display:none;margin-top: -15px;" id="TopSub" >
            <br>หัวข้อย่อย : <select id="SelectSubmain" class="SelectSubmain" ></select><span id="sTSub"/>     
            </div>
                
            </td>
            </tr>
      
            <tr>
            <br><td width="50%" align="right">ภาพประกอบ :</td>
            <td width="70%"><input name="pProPic" type="file" id="pProPic" /><span id="sPic"/></td>
            </tr>
      
            <tr>
            <td width="50%" align="right">จำนวน :</td>
            <td width="70%"><input name="pProQuan" type="text" id="pProQuan" size="1" /><span id="sQuan"/></td>
            </tr>
         
            </table>
            
            รายละเอียด :
            <textarea class="ckeditor" id="pProDetail" ></textarea><span id="sText"/> 
            <input type="submit" id="btnSubmit"  value="Save" />
            
            
           
            <br>
            </div>     

  $("#Selecttopmain").change(function() {
       
       var para = $("#Selecttopmain").val();
       
       $.post("" + baseUrl +"/shop_entityController/findTopSub",{
        
         pTopMain: para,  
         //TopMainID: para,
       },
      function(data){
          $("#TopSub").fadeIn("slow");
          
            var rs = jQuery.parseJSON(data);
        
            $('#SelectSubmain').empty();  
            $('#SelectSubmain').append($('<option>').text("ไม่ระบุ").attr('value', "ไม่ระบุ"))  
            for( var i=0; i<rs.length; i++){
                $('#SelectSubmain').append($('<option>').text(rs[i].TopName).attr('value', rs[i].TopID));            
             }
                      
       
      });
          
    });

 public function AddProductVal() {
           
   $config['upload_path'] = './uploads';      
   $config['allowed_types'] = 'gif|jpg|png|doc|txt';
   $config['max_size'] = 1024 * 8;
   
   $config['encrypt_name'] = TRUE;
   
   $this->load->library('upload', $config);

      if (!$this->upload->do_upload("pProPic"))
      {
         $status = 'error';
          $msg = $this->upload->display_errors('<p>', '</p>');
      }
      else
      {
          $w = $this->upload->data();
          
          $data = array(
             "ProID" => $this->input->Post('pProID'),
             "ProModel" => $this->input->Post('pProModel'),
             "ProName" => $this->input->Post('pProName'),
             "ProPrice" => $this->input->Post('pProPrice'),
             "ProQuan" => $this->input->Post('pProQuan'),
             "ProParent" =>$this->input->Post('Selecttopmain'),
             "ProSub" =>$this->input->Post('SelectSubmain'),
             "Prodetail" =>$this->input->Post('pProDetail'),
             'ProPic' => $w['file_name'],
                                    
         );
         $this->db->insert('shop_product', $data); 
      }

    $this->ShowInsert($this->input->Post('pProID'));
}