从XPathNodeIterator获取数据

我有一个XPathNodeIterator xpProducts，它包含一个类似的XML

<estocklevel>0</estocklevel>
<weightingram>0</weightingram>
<unit></unit>
<volume>0</volume>
<discountgroup></discountgroup>
<manufactor>31862244</manufactor>
<deliverydate>1900-01-01T00:00:00</deliverydate>
<dayscreated extra="dayscreated">41489</dayscreated>

现在我想在一个字符串中获取每个节点的数据，我已经尝试了一些类似的东西

 string  strProductID = xpProducts.Current.Select("/manufactor");

但是它抛出了一个错误

Error   3   Cannot implicitly convert type 'System.Xml.XPath.XPathNodeIterator' to 'string' D:'Projects'20-06-2013-Files'App_Code'DataFetcher.cs    55  28  D:'Projects'20-06-2013-Files'

是否无法从XPathNodeIterator中获取字符串数据？

string strProductID = null;
XPathNavigator navProductID = xpProducts.Current.SelectSingleNode("manufactor");
if(navProductID != null)
{
  strProductID = navProductID.Value;
}