Ext:RowLayout和ColumnLayout连用必须加panel的问题

<ext:RowLayout ID="RowLayout1" runat="server" Split="false">
                                                <Rows>
                                                    <ext:LayoutRow RowHeight=".5">
                                                        <ext:Panel runat="server">
                                                            <Items>
                                                                <ext:ColumnLayout ID="ColumnLayout1" runat="server" Split="false" FitHeight="true">
                                                                    <Columns>
                                                                        <ext:LayoutColumn ColumnWidth=".5">
                                                                            <ext:Panel ID="Panel7" runat="server" Border="false" ColumnWidth=".5">
                                                                                <Content>
                                                                                    <div id="colRealContrast">
                                                                                    </div>
                                                                                </Content>
                                                                            </ext:Panel>
                                                                        </ext:LayoutColumn>
                                                                        <ext:LayoutColumn ColumnWidth=".5">
                                                                            <ext:Panel ID="Panel8" runat="server" Border="false" ColumnWidth=".5">
                                                                                <Content>
                                                                                    <div id="pieRealContrast">
                                                                                    </div>
                                                                                </Content>
                                                                            </ext:Panel>
                                                                        </ext:LayoutColumn>
                                                                    </Columns>
                                                                </ext:ColumnLayout>
                                                            </Items>
                                                        </ext:Panel>
                                                    </ext:LayoutRow>
                                                    <ext:LayoutRow RowHeight=".5">
                                                        <ext:Panel runat="server">
                                                            <Items>
                                                                <ext:ColumnLayout ID="ColumnLayout2" runat="server" Split="false" FitHeight="true">
                                                                    <Columns>
                                                                        <ext:LayoutColumn ColumnWidth=".5">
                                                                            <ext:Panel ID="Panel10" runat="server" Border="false" ColumnWidth=".5">
                                                                                <Content>
                                                                                    <div id="colRiseContrast">
                                                                                    </div>
                                                                                </Content>
                                                                            </ext:Panel>
                                                                        </ext:LayoutColumn>
                                                                        <ext:LayoutColumn ColumnWidth=".5">
                                                                            <ext:Panel ID="Panel11" runat="server" Border="false" ColumnWidth=".5">
                                                                                <Content>
                                                                                    <div id="pieRiseContrast">
                                                                                    </div>
                                                                                </Content>
                                                                            </ext:Panel>
                                                                        </ext:LayoutColumn>
                                                                    </Columns>
                                                                </ext:ColumnLayout>
                                                            </Items>
                                                        </ext:Panel>
                                                    </ext:LayoutRow>
                                                </Rows>
                                            </ext:RowLayout>

 <ext:LayoutRow RowHeight=".5">下不加panel时，会提示错误