Adding an image to WebParts DeclarativeCatalog

I try to add an image banner as a catalog item, but it won't show the image at all. Do I have to wrap it in something or add a custom webpart for this functionality?

When I add the exact same code in an ordinary WebPartZone it shows the image correctly.

<asp:CatalogZone ID="CatalogZone1" runat="server">
    <ZoneTemplate>
        <asp:PageCatalogPart ID="PageCatalogPart1" runat="server" />
        <asp:DeclarativeCatalogPart ID="DeclarativeCatalogPart1" runat="server" >
            <WebPartsTemplate>
                <asp:Image ID="Image1" ImageUrl="..." runat="server" />
            </WebPartsT开发者_运维百科emplate>
        </asp:DeclarativeCatalogPart>
    </ZoneTemplate>
</asp:CatalogZone>