I'm trying to load a treeview. This code works in WinForms. In ASP I get the compile time error

'System.Xml.Linq.Extensions.Nodes<T>(System.Collections.Generic.IEnumerable<T>)' is a 'method', 
which is not valid in the given context

Here's my code. It's erroring on "nodRoot.Nodes.Add(nodReport)" inside the ELSE.

private void _LoadReportNodes()
{
    string Command = "SELECT * FROM ApexReports ORDER BY ParentId, Sequence";
    DataSet dsTreeNodes = DataLayer.ExecuteQuery(Command);

    string ReportTitle = string.Empty;
    TreeNode nodRoot = null;
    TreeNode nodReport = null;

    foreach (DataRow Row in dsTreeNodes.Tables[0].Rows)
    {
        ReportTitle = Row["ReportTitle"].ToString();

        if (Row["ParentId"] != DBNull.Value)
        {
            nodRoot = new TreeNode(ReportTitle);
            tvwReports.Nodes.Add(nodRoot);
        }
        else
        {
            nodReport = new TreeNode(ReportTitle);
            nodRoot.Nodes.Add(nodReport);
        }
    }
}