Transaction problem in asp.net c#

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ASP.NET

I have the following code that is in click event of a button. When I click the button then it takes much time and it shows the following message.

Server Error in '/ERP' Application.
ExecuteReader requires the command to have a transaction when the connection assigned to the command is in a pending local transaction.  The Transaction property of the command has not been initialized.

My code is as below:

protected void btnSave_Click(object sender, EventArgs e)
    {
        //lblErrmsg.Text = "Saving.Please wait....";
        SqlTransaction transaction;
        cn.Open();
        transaction = cn.BeginTransaction();
        try
        {
            SqlCommand cmdd = new SqlCommand("BOM_PO_Delete", cn, transaction);
            cmdd.CommandType = CommandType.StoredProcedure;
            cmdd.Parameters.AddWithValue("@Styleid", lblStyleid.Text);
            cmdd.ExecuteNonQuery();
            for (int i = 0; i < grdPODtl.Rows.Count; i++)
            {
                CheckBox chkselect = (CheckBox)grdPODtl.Rows[i].FindControl("chkselect");
                if (chkselect.Checked == true)
                {
                    Label lbllot = (Label)grdPODtl.Rows[i].FindControl("lbllot");
                    Label lblqty = (Label)grdPODtl.Rows[i].FindControl("lblqty");
                    SqlCommand cmddl = new SqlCommand("BOM_PO_Save", cn, transaction);
                    cmddl.CommandType = CommandType.StoredProcedure;
                    cmddl.Parameters.AddWithValue("@Styleid", lblStyleid.Text);
                    cmddl.Parameters.AddWithValue("@Lot", lbllot.Text);
                    cmddl.Parameters.AddWithValue("@qty", lblqty.Text);
                    cmddl.ExecuteNonQuery();
                }
            }
            SqlCommand cmdd2 = new SqlCommand("BOM_PO_Update", cn, transaction);
            cmdd2.CommandType = CommandType.StoredProcedure;
            cmdd2.CommandTimeout = 400;
            cmdd2.Parameters.AddWithValue("@styleid", lblStyleid.Text);
            cmdd2.ExecuteNonQuery();
            transaction.Commit();
            lblErrmsg.Text = "Saved Successfully";
        }
        catch (Exception ex)
        {
            lblErrmsg.Text = ex.Message;
            transaction.Rollback();
        }
        finally
        {
            transaction.Dispose();
            cn.Close();
        }         
    }