title: Works in SSRS 2012, SSRS 2008 says "Report item expressions can only refer to fields within the current dataset scope"
body: <p>Here's an expression in the header of my report:</p>
  
  <pre><code>="Display value " &amp; Lookup(Parameters!CycleID.Value, Fields!CycleID.Value, Fields!CycleDateDisplay.Value, "DSCycle")
  </code></pre>
  
  <p><code>CycleID</code> and <code>CycleDateDisplay</code> are columns in the Dataset <code>DSCycle</code>. This works great in SSRS 2012, but when I try to upload the same report into SSRS 2008R2, I get this error:</p>
  
  <pre><code>The Value expression for the text box ‘Textbox5’ refers to the field ‘CycleID’. Report item expressions can only refer to fields within the current dataset scope or, if inside an aggregate, the specified dataset scope. (rsFieldReference)
  </code></pre>
  
  <p>(and the same for CycleDateDisplay.)</p>
  
  <p>I'm trying to figure out how to modify this expression to satisfy the "dataset scope" issue here. I consulted TechNet at <a href="http://technet.microsoft.com/en-us/library/cc879331%28v=sql.105%29.aspx" rel="nofollow">http://technet.microsoft.com/en-us/library/cc879331%28v=sql.105%29.aspx</a> and got this information: </p>
  
  <blockquote>
    <p>To specify a scope parameter, provide the name of a dataset, data region, or group that is in scope for the report item. When a report has more than one dataset, an aggregate expression in a text box <strong>on the report body</strong> must specify a scope parameter. For example, <code>=First(Fields!FieldName.Value, "DataSet1")</code></p>
  </blockquote>
  
  <p>(emphasis added) Now is it possible that I can't use expressions of this kind in the header, since the TechNet text went out of its way to specify expressions on the report body? Or if I can, how do I specify columns from a dataset to be used in a <code>LOOKUP()</code> call?</p>
  
  <p>Thank you!</p>