RadWindow does not display inner text

[Roman]

    <telerik:RadWindow ID="winError" runat="server" Skin="Sunset"
        VisibleOnPageLoad="True" Behaviors="Close" Visible="False" Behavior="Close"
        VisibleStatusbar="False" VisibleTitlebar="False">
        <ContentTemplate>
            <asp:Label ID="lblErrorMessage" runat="server" />
        </ContentTemplate>
    </telerik:RadWindow>

I'm using the code and on server side whenever I got an error I populate lblErrorMessage text and make window visible. I always have an empty window popup also my intellisence tells me that: "Element 'contenttemplate' is not supported". What I'm doing wrong?

Thank you,
Roman.

[Roland]

1. Make sure you have the newest Telerik assembly. (Q3) - ContentTemplate is supported only in Q3 2009.

2. In code:

var lbl= wndAddTask.ContentContainer.FindControl("lblErrorMessage") as Label;

lbl.Text = "my Message";