仅读取XML节点

我在获取XML的值时遇到了一个问题，当我调试时，它正在XML文档中加载它，但它没有找到我想要访问的值或节点。这是xml文件。我想要获取的值是"Active"。现在这个XML不是一个文件或任何东西，是作为一个字符串传递…(不能修改这部分)只能访问类，我可以创建函数来访问它，但不能修改实际代码获取值并将其作为"xml字符串"传递

<Clients>
  <BillingCycle>30</BillingCycle>
  <Category>1</Category>
  <Type>Admin</Type>
  <AddressCat>3</AddressCat>
  <ZipCodeCat>5</ZipCodeCat>
  <ClientManager>
    <UserID>5</UserID>
    <ZPVal>1</ZPVal>
    <DRY1>Test</DRY1>
    <Active>1</Active>
  </ClientManager>
</Clients>

这里的c#代码

public bool IsActive(int ClientID, int VassID)
        {
            bool isActive = false;
            HelperClass helper = new HelperClass();
            XmlDocument xml = new XmlDocument();
            //at this point i can see the data was stored in the xml when debugging
            xml.LoadXml(helper.GetClientXML(ClientID, VassID));
           //have tried the following do not woerk
         //   XmlNode node = xml.SelectSingleNode ("/Clients/ClientManager/Active/text()");
            XmlNode node = xml.SelectSingleNode("Clients/ClientManager/Active");
            int isActiveVal = Convert.ToInt32(node.Value);
            if (isActiveVal == 1)
            {
                isActive = true;
            }
            return isActive;
        }

//XmlNode node = xml.SelectSingleNode ("/Clients/ClientManager/Active/text()");
var activeTextNodes = xml.SelectNodes("/Clients/ClientManager/Active/text()");

XmlNode node = xml.SelectSingleNode("Clients/ClientManager/Active");
int isActiveVal = Convert.ToInt32(node.InnerText);

XmlNode node = xml.SelectSingleNode("Clients/ClientManager/Active");
int isActiveVal = Convert.ToInt32(node.FirstChild.Value);