Filling a drop down list from db at IndexChanged

[FastEddie]

I am attempting to fill a drop down list (from a database) once I choose a value from another drop down list. For instance the first drop down list is named ddlYear. When I select the year I want the next list to fill with all the makes from that year. Here is the code I have so far.

Protected Sub ddlYear_SelectedIndexChanged( _
        ByVal sender As Object, _
        ByVal e As System.EventArgs) Handles ddlYear.SelectedIndexChanged
 
        If IsPostBack = True Then
            Dim cnn As New OleDbConnection(obConn)
            Dim cmd As New OleDbCommand
            cmd = cnn.CreateCommand
            cmd.Connection = cnn
            Dim da As New OleDbDataAdapter
            Dim dsMake As New DataSet
            Try
                cnn.Open()
                cmd.CommandText = "Select Make From tblRecall Where Year = '" & _
                    ddlYear.Text & "'"
                da.SelectCommand = cmd
                da.Fill(dsMake, "Makes")
                ddlMake.DataSource = dsMake.Tables("Makes")
                ddlMake.DataMember = ("Makes")
            Catch ex As Exception
                WriteLine(ex.Message)
            Finally
                cnn.Close()
                da.Dispose()
            End Try
        End If
    End Sub

After I select the year nothing at all happens. What am I doing wrong?