title: WebForms ReportViewer Datasource error
body: <p>I use ReportViewer control on my form:</p>
  
  <pre><code>&lt;form id="form1" runat="server"&gt;
      &lt;asp:ScriptManager ID="ScriptManager1" runat="server"&gt;
      &lt;/asp:ScriptManager&gt;
      &lt;rsweb:ReportViewer ID="ReportViewer1" runat="server"&gt;
      &lt;/rsweb:ReportViewer&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>Report file path initialized in page code file:</p>
  
  <pre><code>protected void Page_Init(object sender, EventArgs e)
  {
      ReportViewer1.LocalReport.ReportPath = "Reports/Source/Untitled.rdlc";
  }
  </code></pre>
  
  <p>When report renders, I got next error: </p>
  
  <pre><code>A data source instance has not been supplied for the data source 'DataSet1'.
  </code></pre>
  
  <p>Connection works normally (I tested it), and when I try to run my report in MS SQL Server Report Builder - it works normally too (report was generated).</p>