Child of Columnchildren only can be Panel.

<columnlayout>
    <columnchildren width="30%" style="padding: 5px">    
        <panel height="100px" style="margin-bottom:10px"        
            title="column1-1" border="normal" maximizable="true" collapsible="true">            
            <panelchildren>Panel</panelchildren>            
        </panel>        
        <panel height="100px" framable="true" title="column1-2"        
            border="normal" maximizable="true" style="margin-bottom:10px">            
            <panelchildren>Panel</panelchildren>            
        </panel>        
        <panel height="100px" title="column1-3" border="normal" closable="true">        
            <panelchildren>Panel</panelchildren>            
        </panel>        
    </columnchildren>    
    <columnchildren width="40%" style="padding: 10px">    
        <panel title="Data" maximizable="true" border="normal" style="margin-bottom:10px">        
            <panelchildren>            
                <grid fixedLayout="true" style="border:0px" height="100%">                
                    <columns>                    
                        <column label="category" />                        
                        <column label="value" />                        
                    </columns>                    
                    <rows>                    
                        <row>                        
                            <label id="c0" value="C/C++" />                            
                            <decimalbox id="v0" value="21.2"                            
                                constraint="no empty" onChange="update(0)" />                                
                        </row>                        
                        <row>                        
                            <label id="c1" value="VB" />                            
                            <decimalbox id="v1" value="10.2"                            
                                constraint="no empty" onChange="update(1)" />                                
                        </row>                        
                        <row>                        
                            <label id="c2" value="Java" />                            
                            <decimalbox id="v2" value="40.4"                            
                                constraint="no empty" onChange="update(2)" />                                
                        </row>                        
                        <row>                        
                            <label id="c3" value="PHP" />                            
                            <decimalbox id="v3" value="28.2"                            
                                constraint="no empty" onChange="update(3)" />                                
                        </row>                        
                    </rows>                    
                </grid>                
            </panelchildren>            
        </panel>        
        <panel border="normal">        
            <panelchildren>            
                <checkbox label="3D Chart" checked="true"                
                    onCheck="mychart.setThreeD(self.isChecked())" />                    
                <chart id="mychart" title="Pie Chart Demo" width="320px"                
                    type="pie" threeD="true" fgAlpha="128">                    
                    <attribute name="onClick">                    
                            String areaid = event.getArea();                             
                            if (areaid!= null) {                             
                            Area area = self.getFellow(areaid);                            
                            alert(""+area.getAttribute("entity")+":"+area.getTooltiptext());                            
                            }                            
                        </attribute>                        
                    <zscript>                    
                            void update(int rowIndex) {                             
                            Label lb = (Label) self.getFellow("c"+rowIndex);                            
                            Decimalbox db = (Decimalbox)self.getFellow("v"+rowIndex);                            
                            model.setValue(lb.value, newDouble(db.getValue().doubleValue())); }                            
                            PieModel model = new SimplePieModel();                            
                            for(int j=0; j &lt; 4; ++j) { update(j); }                            
                            mychart.setModel(model);                            
                        </zscript>                        
                </chart>                
            </panelchildren>            
        </panel>        
    </columnchildren>    
</columnlayout>