An expression of non-boolean type

Question

Hello Team,

Please am working on Window Application and I have the following table tblProduct which contain the pName as product name , tblDetail contain qty, price and amount, and tblMain contain transaction date as mDate and when I call the data into dataGridView by clicking load buttong I get this error as shown in the screen shot, kindly help

 private void btnLoadData_Click(object sender, EventArgs e)
        {

            double _total = 0;
            int i = 0;
            dataGridView3.Rows.Clear();
            con.Open();
            cmd = new SqlCommand(@"select p.ProID, p.pName,d.price,d.qty,sum(d.amount) from tblDetails as d inner join tblProduct as p on d.ProductID=p.ProID where mDate between'%" + dtSales1.Value.ToString("dd-MM-yyyy") + "'and '" + dtSales1.Value.ToString("dd-MM-yyyy") + "%'group by p.pName, d.price, d.qty, d.amount", con);
            dr = cmd.ExecuteReader();
            while (dr.Read())
            {
                i += 1;
                _total += double.Parse(dr["amount"].ToString());
                dataGridView3.Rows.Add(i, dr["ProID"].ToString(), dr["pName"].ToString(), Double.Parse(dr["price"].ToString()).ToString("#,##0.00"), dr["qty"].ToString(), Double.Parse(dr["amount"].ToString()).ToString("#,##0.00"));
            }
            dr.Close();
            con.Close();
            lblTotal.Text = _total.ToString("Ghc #,##0.00");

            con.Open();
            cmd = new SqlCommand("select isnull(sum(amount),0) from tblDetails where  where mDate between'" + dtSales1.Value.ToString("dd-MM-yyyy") + "'and '" + dtSales2.Value.ToString("dd-MM-yyyy") + "'", con);
            lblTotal.Text = Double.Parse(cmd.ExecuteScalar().ToString()).ToString("#,##0.00");
            con.Close();

        }