我在nz_gdlist.action中无法获取到Mchz，请高手指教!!!

<sx:tabbedpanel
id="tab1"
cssStyle="width: 735px; height: 352px;"
doLayout="true"
labelposition="top">
<sx:div id="left"
label="名称信息">


<table align="center" width="731" border="1" cellspacing="1" cellpadding="2">
<tr>
          <td width="90">内部序号</td>
          <td width="275"><s:textfield size="35" name="mchz.nbxh"/></td>
          <td width="90">企业名称</td>
          <td width="275"><s:textfield size="35" name="mchz.qymc"/></td>
        </tr>
        <tr>
          <td width="90">内部序号</td>
          <td width="275"><s:textfield size="35" name="mchz.nbxh"/></td>
          <td width="90">企业名称</td>
          <td width="275"><s:textfield size="35" name="mchz.qymc"/></td>
        </tr>
        <s:iterator id="list" value="mchz.qymchzgds" >
        <td width="90">内部序号</td>
        <tr>
         <td>${list.tzje}</td>
        </tr>
        <td width="90">企业名称</td>
        <tr>
         <td>${list.rjje}</td>
        </tr>
        </s:iterator>
    </table> </sx:div>
<sx:div id="middle" 
label="股东信息">
<iframe width=734 height=350 marginwidth=0 marginheight=0 hspace=0 frameborder=1 scrolling=yes src=nz_gdlist.action?Mchz=${mchz}></iframe>

</sx:div>
</sx:tabbedpanel>