Problem in DataBinding with two Combo box using c#

Question

hello every one,

i have very big problem i have 2 combo box which is bind from database when i m changing one combo box than its not working properly i dont know why its give me exception i m sending code of binding..  please check it now and reply me as soon as possible ...........

//code

 // show bank details for deposit bank 

        private void show_bank_info()

        {

            try

            {

                

                cb_bank_name.Items.Add("Select Bank Name");

                DataSet ds = new DataSet();

                ds = gBL.show_bank_name_place();

                DataRow r = ds.Tables[0].NewRow();

                r["Bank_Name"] = "Select Bank Name";

                ds.Tables[0].Rows.InsertAt(r, 0);

                cb_bank_name.DataSource = ds.Tables[0];               

                cb_bank_name.DisplayMember = "Bank_Name";

                cb_bank_name.ValueMember = "Bank_Id";

                cb_bsr_code.DataBindings.Clear();

                cb_bsr_code.DataBindings.Add("text", ds.Tables[0], "BSR_Code");

            }

            catch (Exception ex)

            {

                MessageBox.Show(ex.Message);

            }

        }

        // show bsr code 

        private void show_Bsr_Code()

        {

            try

            {

                cb_bsr_code.Items.Add("Select BSR Code");

                DataSet ds = new DataSet();

                ds = gBL.show_bank_name_place();

                DataRow r = ds.Tables[0].NewRow();

                r["Bsr_Code"] = "Select BSR Code";

                ds.Tables[0].Rows.InsertAt(r, 0);

                cb_bsr_code.DataSource = ds.Tables[0];

                cb_bsr_code.DisplayMember = "BSR_Code";

                cb_contract_description.ValueMember = "Bank_Id";

                cb_bank_name.DataBindings.Clear();

                cb_bank_name.DataBindings.Add("text", ds.Tables[0], "Bank_Name");

            }

            catch (Exception ex)

            {

              MessageBox.Show(ex.Message);

            }

        }

reply me as soon as possible