title: Sort table by parameter (Reporting Services 2008)
body: <p>In Reporting Services 2008, I would like to sort a table by the use of a parameter.
  The table has fields MainCategory and SubCategory. My parameter is called SortCriterion and has two labels, "Main Category" and "Sub Category".
  The sortexpression of the table should then be </p>
  
  <pre><code>=Parameters!SortCriterion.Value
  </code></pre>
  
  <p>But I do not know what to insert as value for the parameters. Naively, I tried</p>
  
  <pre><code>Fields!MainCategory.Value
  </code></pre>
  
  <p>and </p>
  
  <pre><code>Fields!SubCategory.Value
  </code></pre>
  
  <p>but it doesn´t work. Is it possible and how?</p>