With this code, it always inserts NULL in the "eier"-field when editing the record. (But the item's is showing in the dropdownlist as it should and everything else is okay):

<asp:TemplateField HeaderText="Eier" SortExpression="Eier">
    <EditItemTemplate>
        <asp:DropDownList ID="DropDownListBildeEier" runat="server" DataSourceID="SqlDataSourceEiernavn"
        DataTextField="Eier" DataValueField="Eier" SelectedValue='<%# Bind("Eier") %>'></asp:DropDownList>

    </EditItemTemplate>
    <ItemTemplate>
        <asp:Label ID="Label1" runat="server" Text='<%# Bind("Eier") %>'></asp:Label>
    </ItemTemplate>
</asp:TemplateField>

And: If I put comment round the asp:DropDownList and remove the comment round the asp:TextBox, everything is working ok.