Losing values in 2 CallBackPanels when updating the other.

Not sure if anyone is using Obout and their Ajax features but if you are and you can help me, you are a life saver:

I have 2 panels that have drop downs in both.
I update the drop downs from the server and when I update 1 panel, I loss the values in the other panel. Can anyone explain what I am doing wrong?

I have included attachments and code.

HTML:
<script>
function ChangeGroup() {
            ob_post.post(null, "onloadGroup", function(){});
      }
function CurrentDate() {
      var dStartDay = document.getElementById('ddlStartDay').value;
      var dStartMonth = document.getElementById('ddlStartMonth').value;
      var dStartYear = document.getElementById('ddlStartYear').value;
      
      alert(dStartMonth + "/" + dStartDay + "/" + dStartYear);
            
      ob_post.post(null, "onDate", function(){});
      }
</script>

<oajax:CallbackPanel id="cpPanel1" runat="server">
    <CONTENT>
        <asp:dropdownlist id="ddlDropDown" runat="server" Width="168px" AutoPostBack="false"></asp:dropdownlist>
    </CONTENT>
    <LOADING style="HEIGHT: 1px">
          <TABLE height="100%" cellSpacing="0" cellPadding="0" width="100%">
                <TR>
                      <TD vAlign="center" align="middle"></TD>
                </TR>
          </TABLE>
    </LOADING>
</oajax:CallbackPanel>
<oajax:CallbackPanel id="cpPanel2" EnableViewState="true" RenderMethod="Always" Visible="true" ShowLoading="true" runat="server">
    <CONTENT>
        <SELECT id="ddlStartMonth" style="FONT-WEIGHT: bold; FONT-SIZE: xx-small; FONT-FAMILY: Verdana" runat="server" NAME="ddlStartMonth"></SELECT>
          <SELECT id="ddlStartDay" style="FONT-WEIGHT: bold; FONT-SIZE: xx-small; FONT-FAMILY: Verdana"  runat="server" NAME="ddlStartDay"></SELECT>
          <SELECT id="ddlStartYear" style="FONT-WEIGHT: bold; FONT-SIZE: xx-small; FONT-FAMILY: Verdana"  runat="server" NAME="ddlStartYear"></SELECT>
    </CONTENT>
    <LOADING style="HEIGHT: 1px">
          <TABLE height="100%" cellSpacing="0" cellPadding="0" width="100%">
                <TR>
                      <TD vAlign="center" align="middle"></TD>
                </TR>
          </TABLE>
    </LOADING>
</oajax:CallbackPanel>      

<asp:button id="btnDate" runat="server" Font-Bold="True" Font-Size="XX-Small" Font-Names="Verdana" Text="What is the date" Width="120px" CausesValidation="False"></asp:button><BR>

Vb Code behind:
      Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim i As Integer

        If Not Page.IsPostBack Then
            'Pop day
            For i = 1 To 31
                ddlStartDay.Items.Add(i)
                ddlStartDay.Items.FindByText(i).Value = i
            Next
            ddlStartDay.Value = System.DateTime.Today.Day

            'Pop month
            For i = 1 To 12
                ddlStartMonth.Items.Add(i & "-" & MonthName(i, False))
                ddlStartMonth.Items.FindByText(i & "-" & MonthName(i, False)).Value = i
            Next
            ddlStartMonth.Value = System.DateTime.Today.Month

            'PopYear
            For i = -2 To 2
                ddlStartYear.Items.Add(System.DateTime.Today.Year + i)
                ddlStartYear.Items.FindByText(System.DateTime.Today.Year + i).Value = System.DateTime.Today.Year + i
            Next
            ddlStartYear.Value = System.DateTime.Today.Year

            ddlDropDown.Items.Add("Selection 1")
            ddlDropDown.Items.Add("Selection 2")
        End If

        ddlDropDown.Attributes.Add("onchange", "ChangeGroup();return false;")
        btnDate.Attributes.Add("onclick", "CurrentDate();return false;")
    End Sub

    Public Sub onloadGroup()
        ShowAlert(ddlDropDown.SelectedItem.Value)

        ddlDropDown.Items.Clear()
        ddlDropDown.Items.Add("Selection 3")
        ddlDropDown.Items.Add("Selection 4")

        UpdatePanel("cpPanel1")
    End Sub

    Public Sub onDate()
        ShowAlert(ddlStartMonth.Value & "/" & ddlStartDay.Value & "/" & ddlStartYear.Value)

        UpdatePanel("cpPanel2")
    End Sub