Web Forms :: Populating Dropdownlist From Session Variable?

To speed things up for the visitor of my web page, I put a personalised dropdownlist in a session variable (as below).

The idea is that if the user is logged in and the ddl session variable is Nothing then it should be set here, and the next times the dropdownlist should be set from this session variable.

The session seems to be populated ok, but the resulting dropdownlist (ddlMenu) doesn't (it just becomes blank). I suspect that it has soemething to do with the way I try to assign it. No matter what I try I run into problems, saying that one thing is a one-dimensional array and the other thing a listitemcollection, or the like. What should I write in the last line?

If Session("aid") IsNot Nothing And Session("ddl") Is Nothing Then
Dim ddlny As New DropDownList
ddlny.Items.Add(New ListItem(vstr, ""))
ddlny.Items.Add(New ListItem(kontrstr, "PageA.aspx"))
ddlny.Items.Add(New ListItem(bstr, "PageB.aspx"))
If dt IsNot Nothing Then 'dt is a datatable, populated elsewhere
For i As Integer = 0 To dt.Rows.Count - 1
ddlny.Items.Add(New ListItem(dt.Rows(i).Item("name"), dt.Rows(i).Item("did")))
Next
End If
Session("ddl") = ddlny
End If
ddlMenu.Items.Clear()
ddlMenu = Session("ddl") 'THIS IS THE LINE THAT SHOULD BE REWRITTEN.