Change visbilty of datalist labels after binding using code

I have  Table   named    PRODUCTS , that have 4  column   productid, productprice,productname & discount( type  numeric(18,0)) .. i am using datalist with itemtemplate that have  4  label to display all ..

i am binding datalist on pageload, now i want that Label4  with "discount" should only visible for those product that have discount , otherwise it remains hidden, 

problem in my code is that when i run it , label becomes invisible for all  products whether they have discount or not .  kindly guide me.. 

here is my code i am using for it:

ds1  is my dataset 

 foreach (DataListItem item in DataList1.Items)

                        {

                            for (int i = 0; i <= ds1.Rows.Count - 1; i++)

                            {

                                double[] arr = new double[ds1.Rows.Count];

                                double temp = double.Parse(ds1.Rows[i]["discount"].ToString());

                                arr[i] = temp;

                                Label lbl = item.FindControl("Label4") as Label;

                                if (arr[i] == 0)

                                    lbl.Visible=false;

                            }

                   }