```
<asp:SqlDataSource ID="SqlDataSource8" runat="server" ConnectionString="<%$ ConnectionStrings:SqlDataSource1 %>" SelectCommand="SELECT SUM(Summe), ItemObjektID FROM [Item] GROUP BY ItemObjektID"></asp:SqlDataSource>
             Items:<br /><asp:GridView ID="GridView1" runat="server" AllowPaging="True" AllowSorting="True" AutoGenerateColumns="False" DataKeyNames="ItemObjektID" DataSourceID="SqlDataSource8">
         <Columns>
            <asp:BoundField DataField="ItemObjektID" HeaderText="ItemObjektID" InsertVisible="False" ReadOnly="True" SortExpression="ItemObjektID" />
            <asp:BoundField DataField="Summe" HeaderText="Summe" SortExpression="Summe" />
        </Columns>
    </asp:GridView>

```

Thats my Code and I get the Error Message that the Name or Entry Summe does not exist?