Datagridview not populating

Question

i have a method private void FillLevyRoll(), i put the method in a button on click event to fill a datagridview dgvLevyRoll my problem is when i run i am not getting an error and the dgv is remaining empty.Im lost confused tried but to no avail.

The query works in SQL management studio

private void FillLevyRoll()
   {
       try
       {
           DataTable dataTableSource = new DataTable();


           SqlCommand command = new SqlCommand("SELECT  Refrence" +
               ", MAX(CASE WHEN AccNumber = '1010000' THEN amount END) AS Opening" +
               ", MAX(CASE WHEN AccNumber = '1010000' THEN amount END) AS electricity" +
               ", MAX(CASE WHEN AccNumber = '1045000' THEN amount END) AS water" +
               ", MAX(CASE WHEN AccNumber = '1000000' THEN amount END) AS levy" +
               ", MAX(CASE WHEN AccNumber = '2750000' THEN amount END) AS Interest" +
               ", MAX(CASE WHEN AccNumber = '4000000' THEN amount END) AS Legal" +
               ", MAX(CASE WHEN AccNumber = '4350003' THEN amount END) AS Other" +
               ", MAX(CASE WHEN AccNumber = '8400000' THEN amount END) AS Payments" +
               ", MAX(CASE WHEN AccNumber = '1000000' THEN amount END) AS Due" +
               " FROM dbo.vw_LedgerTransactions" +
               " GROUP BY Refrence ", conn);

           SqlDataAdapter adapter = new SqlDataAdapter(command);
           conn.Open();

           adapter.Fill(dataTableSource);
           dgvLevyRoll.DataSource = dataTableSource;

       }
       catch (Exception ex)
       {
           MessageBox.Show("Application Error. err:" + ex.ToString());
       }
       finally
       {
           conn.Close();
       }

   }