求救：关于正则表达式获取页面某些数据的问题

被抓取的页面代码：
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gbk">
<title>N A C A O 欢 迎 您</title>
<link rel="stylesheet" href="/css/f1.css" type="text/css"><script Language="javascript"> 
function Click(){
alert('禁用！');
window.event.returnValue=false;
}
document.oncontextmenu=Click;
</script></head>
<body leftmargin="0" topmargin="20" marginwidth="0" marginheight="0" onselectstart="return false">
<p><br></p>
<table cellspacing="0" cellpadding="0" width="778" align="center" class="nacao"  border="0">
 
                    

<tr> 
            <td  colspan="3" align="center" valign=top>
  
  </td>
          </tr>

                    <tr valign="middle" > 
                      <td width="14" height="27"  align=left valign="top" background="/images/corner_top1.gif"  ><img src="/images/corner_topleft1.gif" width="14" height="27"></td>
                      <td width="745" height="27" align=right valign="top" background="/images/corner_top1.gif" ><img src="/images/corner_toptu1.gif" width="98" height="27"></td>
                      <td width="19" height="27" align=right valign="top" background="/images/corner_top1.gif"  ><img src="/images/corner_topright1.gif" width="19" height="27"></td>
                    </tr>
                    <tr valign="middle" >
                      <td height="83" align=left valign="top" background="/images/corner_left1.gif"  >&nbsp;</td>
                      <td align=center valign="top" bgcolor="#EFF7FF"  >
<table width="90%" border="0" cellspacing="0" cellpadding="0">
<tr>
<td height="30" colspan="2" align="center" class="nacao"><font color="#FF0000">详细信息</font>
</td>
</tr>
</table>
      <table cellspacing=0 cellpadding=0 width="100%" align=center class="nacao"  border=1>
        <tr> 
          <td height="18" width="20%" align="right" class="nacao"><font color="#0000FF">机构代码：&nbsp;</font></td>
          <td height="18" width="80%" align="left" class="nacao" colspan="3">&nbsp; 
            
            700360787 
            
          </td>
        </tr>
        <tr> 
          <td height="18" width="20%" align="right" class="nacao"><font color="#0000FF">机构名称：&nbsp;</font></td>
          <td height="18" width="80%" align="left" class="nacao" colspan="3">&nbsp; 
            
            北京上海人家餐饮有限责任公司 
            
          </td>
        </tr> 
        
      </table>
<table cellspacing=0 cellpadding=0 width="100%" align=center class="nacao"  border=0>  
  <tr>
    <td height="40" colspan="1" align="center" valign="middle" class="nacao">
      <input name="Submit" type="submit" class="nacao" value="关闭窗口" onClick="window.close()">
    </td>
  </tr>
</table>
</td>
                      <td align=right valign="top" background="../images/corner_right1.gif"  ></td>
                    </tr>
                    <tr valign="middle" >
                      <td align=left valign="top"  ><img src="../images/corner_bottomleft1.gif" width="14" height="30"></td>
                      <td align=middle  background="../images/corner_bottomtu1.gif" ></td>
                      <td align=right valign="top"  ><img src="../images/corner_bottomright1.gif" width="19" height="30"></td>
                    </tr>                    <font color="#3399CC">
                    </table>
                    </font>                    
</body>
</html>xml模板：
<?xml version="1.0" encoding="utf-8" ?> 
<Analyst>
<![CDATA[<font color="#0000FF">机构代码：&nbsp;</font>
            </td>
            <td height="19" bgcolor="#F0F0F0">(?<Code>.*)</td>
          </tr>
          <tr> 
          <td height="18" width="20%" align="right" class="nacao"><font color="#0000FF">机构名称：&nbsp;</font></td>
          <td height="18" width="80%" align="left" class="nacao" colspan="3">&nbsp; 
            (?<Corpname>.*)td>]]>
</Analyst>后台代码：
XmlDocument analystXmlDoc = new XmlDocument();
analystXmlDoc.Load(analystXmlPath);
string pattern = analystXmlDoc.DocumentElement.InnerText;// string strRegex = @"\?<(?<group>[\w]+)>";// MatchCollection matches = Regex.Matches(pattern,strRegex,RegexOptions.IgnoreCase| RegexOptions.Singleline | RegexOptions.Compiled);
MatchCollection matches = Regex.Matches(pageString,pattern,RegexOptions.IgnoreCase| RegexOptions.Singleline | RegexOptions.Compiled); string[] rtnString = new string[matches.Count]; for(int i=0;i<matches.Count;i++)
{
rtnString[i] = matches[i].Value;
}
提问：
我得到的rtnString 值为空的，请问为什么啊？请高手帮忙。