Gridview Total getting NullReferenceError Object reference not set to an instance of an object.

<asp:GridView ID="gvBasket" runat="server" AutoGenerateColumns="False"
    ShowFooter="True" onrowdatabound="gvBasket_RowDataBound">
    <FooterStyle Font-Bold="true" BackColor="#61A6F8" ForeColor="black" />
 <Columns>
        <asp:BoundField DataField="ProductName" HeaderText="Product Name" SortExpression="ProductName" />
        <asp:BoundField DataField="qty" HeaderText="Quantity" SortExpression="qty" />
        <asp:BoundField DataField="UnitPrice" HeaderText="Unit Prce" SortExpression="unitPrice"
            HtmlEncode="false" DataFormatString="{0:c}" />
        <asp:TemplateField HeaderText="Total" SortExpression="Total">
            <ItemTemplate>
                <asp:Label ID="lblTotal" runat="server" Text='<%# Eval("Total","0:c") %>'  />
            </ItemTemplate>
            <FooterTemplate>
            <asp:Label ID="lblsubTotal" runat="server" />

            </FooterTemplate>
        </asp:TemplateField>
        <asp:BoundField DataField="sessionID" HeaderText="Session"
            SortExpression="sessionID" visible="false"/>
        <asp:BoundField DataField="UserID" HeaderText="user" SortExpression="UserID" Visible="false" />
        <asp:BoundField DataField="ProductID" HeaderText="ProductID"
            SortExpression="ProductID" visible="false"/>
        <asp:TemplateField HeaderText="Edit">
            <ItemTemplate>
                <asp:Button ID="Delete" runat="server"
                    CommandArgument='<%# Bind("productID") %>' onclick="Delete_Click"
                    Text="Delete" CommandName="DeleteItem" />
                <asp:Button ID="btnAdd" runat="server"
                    CommandArgument='<%# Bind("productID") %>' CommandName="AddItem"
                    onclick="btnAdd_Click" Text="Add" />
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

        new decimal stotal = 0; 
        protected void gvBasket_RowDataBound(object sender, GridViewRowEventArgs e)       
{
 if (e.Row.RowType == DataControlRowType.DataRow)
 {
Label lblTotal = (Label)e.Row.FindControl("lblTotal");
decimal total = Convert.ToDecimal(DataBinder.Eval(e.Row.DataItem, "Total"));
lblTotal.Text = total.ToString();
stotal += total;
 }
 if (e.Row.RowType == DataControlRowType.Footer)
 {
Label lblTotal = (Label)e.Row.FindControl("lblTotal");
lblTotal.Text = stotal.ToString();
 }
}

string session = Session.SessionID.ToString();

             string Query = "SELECT  tblProduct.ProductName as ProductName, tblProduct.UnitPrice as UnitPrice, sum(ShoppingBasket.qty) as Qty , tblProduct.UnitPrice*sum(ShoppingBasket.qty) as Total, ShoppingBasket.sessionID, ShoppingBasket.userID, ShoppingBasket.productID FROM ShoppingBasket join tblProduct on ShoppingBasket.productID=tblProduct.ProductID where ShoppingBasket.sessionID= '" + session + "' AND ShoppingBasket.UserID='' group by ShoppingBasket.userID, tblProduct.ProductName, tblProduct.UnitPrice, ShoppingBasket.sessionID, ShoppingBasket.productID";



             ConnectionHandler objHandler = new ConnectionHandler();
             DataTable dt = objHandler.ExecuteSelect(Query);


             gvBasket.DataSource = dt;
             gvBasket.DataBind();