ASP.Net DataList RepeatDirection Vertical: Display DataList vertically in ASP.Net

What is the RepeatLayout you are using? It must be set to Table.

And there's no DisplayDirection, you need to set RepeatDirection.

<asp:DataList runat="server" RepeatDirection = "Vertical" RepeatLayout = "Table">
    <ItemTemplate>
    </ItemTemplate>
</asp:DataList>