ZK框架Listbox怎么显示数据

ZK框架Listbox如何显示数据啊
我想加载的时候显示数据，参考了官网的例子，对象有值，但是还是不能显示到listbox上。第一次写ZK，正在摸索阶段，求例子，求指点。

trainReqColl.zul
请看下面Listbox

<?page title="TrainingRequireCollection" contentType="text/html;charset=UTF-8"?>

<zk>

<window title="年度訓練需求收集" border="normal"  id="WinColl"  width="auto" apply="com.web.TrainReqCollController"  position="center,center">

<div align="center">

	<div align="center" width="980px">

		<groupbox closable="false">

			<grid fixedLayout="true">

				<columns>

					<column width="100px" />

					<column width="180px" />

					<column width="130px" />

					<column width="210px" />

					<column width="90px" />

					<column width="210px" />

				</columns>

				<rows>

					<row> 

						<label value="階層   " pre="true" />

						<combobox id="cobPerson_level" autodrop="true" constraint="no empty" readonly="true">

							<comboitem label="課長"></comboitem>

							<comboitem label="經理"></comboitem>

                		</combobox>

						<label value="職等  " pre="true" />

						<combobox id="cobTitle" autodrop="true" constraint="no empty" readonly="true">

							<comboitem label="1"></comboitem>

							<comboitem label="3"></comboitem>

							<comboitem label="5"></comboitem>

                		</combobox>

                		<label value="課程名稱" pre="true" />

                		<combobox id="cobCourseName" autodrop="true" constraint="no empty" readonly="true">

                			<comboitem label="課程名稱1"></comboitem>

                			<comboitem label="課程名稱2"></comboitem>

                			<comboitem label="課程名稱3"></comboitem>

                		</combobox>

					</row>

					<row>

						<label value="時數" pre="true" />

						<intbox id="txtHours" format="0" constraint="no empty,no negative,no zero" />

						<label value="人數" pre="true" />

						<intbox id="txtNumber_of_Person" format="0" constraint="no empty,no negative,no zero" />

						<label value="班次 " pre="true" />

						<intbox id="txtOrder_of_Classes" format="0" constraint="no empty,no negative,no zero" />

					</row>

					<row>

						<label value="內/外訓" pre="true" />

						<radiogroup id="rdoInternalExternal">

							<radio label="內訓" value="0" />

							<space spacing="5px" />

							<radio label="外訓" value="1" />

						</radiogroup>

						<label value="訓練目標與說明" pre="true" />

						<cell colspan="3" style="color: #00547A" valign="top">

							<textbox id="txtTarget_Description" rows="1" width="450px" />

						</cell>

					</row>

					<row>

						<label value="填寫日期" pre="true" />

						<datebox id="dboxInsert_Date" format="yy-MM-dd HH:mm:ss" readonly="true" constraint="no empty" />

						<label value="發送日期" pre="true" />

						<datebox id="dboxSend_Date" format="yy-MM-dd HH:mm:ss" readonly="true" constraint="no empty" />

					</row>

					<row>

						<label value="備註" pre="true" />

						<cell colspan="3" style="color: #00547A" valign="top">

							<textbox id="txtRemark" rows="1" width="450px" />

						</cell>

					</row>

				</rows>

			</grid>

		</groupbox>

		<hbox pack="center" width="980px">

			<button id="btnAdd" label="Add" mold="trendy"

				height="27px" width="55px" />

		</hbox>

	</div>

	<div height="500px">

		<listbox model="@{WinColl.trcModel}"  width="980px" checkmark="true" fixedLayout="true" mold="paging" pageSize="6" emptyMessage="No items match your search">

			<listhead sizable="true">

				<listheader width="30px" />

				<listheader label="階層" width="50px" align="center" />

				<listheader label="職等" width="50px" align="center" />