dynamically generating options for select box

[sbhmf]

in classic asp i do this:

<select name=...>
<%for i=0 to UBound(Session("MyGroupsArray"))%>
<option><%=Session("MyGropupsArray")(i)%></option>
<%next%>
</select>

in asp.net i did:

<tr><td>
<asp:label for="selGroups">Select your default group:</asp:label>
<asp:dropdownlist id="selGroups" runat="server">
<%For i = 0 to UBound(Session("AllGroups"))%>
<asp:listitem><%=Session("AllGroups")(i)%></asp:listitem>
<%Next%>
</asp:dropdownlist></td></tr>

I AM GETTING A BLOOMIN' ERROR !@#$% why?

how do i code a dropdownlist dynamically in .NET?