cart adding problem

[eluser]elombashy[/eluser]
hiii..

I built a website with a codeigniter shopping cart and ajax, and the problem is when i press the add-button, sometimes it adds the items, sometimes it replaces it and sometimes it removes it!
here is my code:

Code:

//html:
<a
class="add_to_cart_btn"
href="main/add_to_cart/&lt;?php echo $categoriesAndProdcuts[$key][$i]['productId']; ?&gt;
">

//jquery:
$('.add_to_cart_btn').click(function(){
        
        href=$(this).attr('href');
        href_array = href.split('/');
        id=href_array[2];
        
        $.ajax({
            type: "post",
            cache: false,
            url: href,
            data: '',
            success: function(data){
                if(data){
                    $("#main_cart").remove();
                    $("#mostVisited").after(data);
                }
            }
        });
        
        $.ajax({
            type: "post",
            cache: false,
            url: 'main/total_cart_products_plus',
            data: '',
            success: function(data){                
                $("#total_cart_products").html(data);
            }
        });
        return false;
    });


//Controller:
function add_to_cart($id) {
        
    $product = $this->cart_m->get($id);
        $products=$this->cart->contents();
        $ids=array();
        foreach ($products AS $k=>$v){
            
            $ids[$k]=$v['id'];
        }
        if(in_array($id, $ids)){
            $rowid = array_search($id, $ids);
            $update_data=array(
                    'rowid'=> $rowid,
                    'qty'  => $v['qty']+1
                );
                $this->cart->update($update_data);
        }
        else{
            $data = array(
                'id' => $id,
                'name' => $product[0]['name'],
                'qty' => 1,
                'price' => $product[0]['price'],
                'image'   => $product[0]['image']            
            );
            $this->cart->insert($data);
            
        }
        $this->load->view('cart/main_cart');
    }

//Model:
function get($id) {
        $data=array();
        $this->db->select('name, price, image')->from('product')
        ->join('product_description','product.product_id=product_description.product_id')
        ->where('product.product_id',$id)->where('language_id',2);
        $results = $this->db->get();
        //var_dump($results);die();
        if($results->num_rows()>0){
            foreach($results->result_array() AS $result){
              $data[]=$result;
            }
        
        }
        return $data;
    }

Any Suggestions??

[eluser]toopay[/eluser]
I hope codeigniter mods apply...

Code:

if(trim($post) == '') die ('You must write something!');