试试这个：

而不是ServerReport

Let try this:
Instead of ServerReport

ReportViewer1.ProcessingMode = ProcessingMode.Remote;
ServerReport serverReport;
serverReport = ReportViewer1.ServerReport;
serverReport.ReportServerUrl = new Uri(ReportServerTextBox.Text);
serverReport.ReportPath = FolderTextBox.Text + ReportNameTextBox.Text;

ReportParameter[] rp = new ReportParameter[1];
rp[0] = new ReportParameter("OrderID", txtOrderID.Text);
ReportViewer1.ServerReport.SetParameters(rp);
ReportViewer1.ServerReport.Refresh();

我已经过测试和工作。

I have tested and worked.