ComboBox SelectedIndex always -1 or 0

[Tim]

I've got two comboboxes with two objectdatasources:

<telerik:RadComboBox ID="RadComboBoxConnection" runat="server" Height="200px" Width="300px"
        Filter="Contains" MarkFirstMatch="true" ChangeTextOnKeyBoardNavigation="false" AllowCustomText="false"
        DataSourceID="ObjectDataSourceConnection" DataTextField="DatabaseFriendlyName" DataValueField="ImportConnectionId" AutoPostBack="true" EnableViewState="true">
</telerik:RadComboBox>

<telerik:RadComboBox ID="RadComboBoxObject" runat="server" Height="200px" Width="300px"
        Filter="Contains" MarkFirstMatch="true" ChangeTextOnKeyBoardNavigation="false" AllowCustomText="false"
        DataSourceID="ObjectDataSourceObject" DataTextField="ObjectName" DataValueField="ImportObjectId" AutoPostBack="true" EnableViewState="true" OnSelectedIndexChanged="RadComboBoxObject_OnSelectedIndexChanged">
</telerik:RadComboBox>

<asp:Literal ID="litMessage" runat="server" />

<asp:ObjectDataSource ID="ObjectDataSourceConnection" runat="server"
    TypeName="Ams.Web.BackOffice.ImportConnectionAdapter"
    DataObjectTypeName="Ams.Core.DomainObject.ImportConnection"
    OldValuesParameterFormatString="original_{0}"
    ConflictDetection="CompareAllValues"
    SelectMethod="SelectImportConnection" />

<asp:ObjectDataSource ID="ObjectDataSourceObject" runat="server"
    TypeName="Ams.Web.BackOffice.ImportObjectAdapter"
    DataObjectTypeName="Ams.Core.DomainObject.ImportObject"
    OldValuesParameterFormatString="original_{0}"
    ConflictDetection="CompareAllValues"
    SelectMethod="SelectImportObject">
        <SELECTPARAMETERS>
            <asp:ControlParameter Name="aImportConnectionId" PropertyName="SelectedValue" ControlID="RadComboBoxConnection" />
        </SELECTPARAMETERS>
    </asp:ObjectDataSource>

The first combobox I have no problems with. I can selected any entry, and on postback it retains its values.
The second combobox however, when selecting a new item, it loses its value every time. Page_Init its SelectedIndex is -1. Page_Load, always 0!! Even when declaring OnSelectedIndexChanged, still 0. ALWAYS 0 or -1!
Any ideas? Thanks in advance.
PS. Also found something really quirky. I can select an entry, then if I deselect (lose the focus of the second combobox) it reverts to the SelectedIndex = 0.

[Tim]

The problem was between the keyboard and chair.
The DataValueField was null / 0 for all entries because the object I was binding to wasn't being initialized properly.