ComboBox DropDown is blank

<?page title="Auto Generated index.zul"?>
<zk>
<window  title="State City Demo" border="normal" >
<zscript>
	<![CDATA[            
	String[] _dict = { 
		"Karnataka", "Punjab", "Kerala", 
		"Tamilnadu", "Manipur" ,
		};
	 ListModel dictModel= new SimpleListModel(_dict);
	 ]]>
</zscript>
 <grid>
    <columns>
    </columns>
    <rows>
        <row>
        <label value="State"/>
		<combobox id="state" readonly="true"  model="${dictModel}"/>
        </row>
        
    </rows>
 </grid>
</window>
</zk>