title: How to sum a column that is based on an expression in SSRS ReportBuilder table
body: <p>If have a column where the value is based on another field, so the expression is </p>
  
  <pre><code>=iif(Fields!TaskType.Value = "Type1", Fields!Amount.Value, 0)
  </code></pre>
  
  <p>And I'm trying to get the sum of this in the group totals using the folooing exporession, but it gives #Error (with or without the group name as scope):</p>
  
  <pre><code>=sum(iif(Fields!TaskType.Value="Type1", Fields!Amount.Value, 0), "GrpProjectNumber")
  </code></pre>
  
  <p>This looks fine to me. What am I doing wrong?
  Thanks in advance</p>