AjaxUpdatedControl RadDropDownList is empty

[Brian]

I have four dropdowns and three of them are working fine. But the last one never receives any values. It does populate with an 'insert item' value from code behind but the remaining data values are failing to populate. This is identical to the other dropdowns. Additionally, this issue is only in a single environment. Development does not have this issue but QA does. The issue is with the ddlActionSubGroup. I just added in the LoadingPanel. But again it works fine in our development environment.

<telerik:RadAjaxManager ID="RadAjaxManager1" runat="server" DefaultLoadingPanelID="RadAjaxLoadingPanel1">
    <AjaxSettings>
        <telerik:AjaxSetting AjaxControlID="ddlBranch">
            <UpdatedControls>
                <telerik:AjaxUpdatedControl ControlID="ddlSalesRoute" LoadingPanelID="RadAjaxLoadingPanel1" />
                <telerik:AjaxUpdatedControl ControlID="ddlAction" LoadingPanelID="RadAjaxLoadingPanel1" />
            </UpdatedControls>
        </telerik:AjaxSetting>
        <telerik:AjaxSetting AjaxControlID="ddlAction">
            <UpdatedControls>
                <telerik:AjaxUpdatedControl ControlID="ddlActionSubGroup" LoadingPanelID="RadAjaxLoadingPanel1" />
            </UpdatedControls>
        </telerik:AjaxSetting>
    </AjaxSettings>
</telerik:RadAjaxManager>
<telerik:RadAjaxLoadingPanel ID="RadAjaxLoadingPanel1" runat="server" InitialDelayTime="0" MinDisplayTime="1000" Transparency="25">
    <div style="background-color: #ffffff; width: 100%; height: 100%"></div>