title: unable to cast of type 'System.Data.EnumerableRowCollection`1[System.String]' to type 'System.IConvertible'
body: <p>I need the column value(FundSpreadDurationContribution) of a data table(residing in dataset) through LINQ which fetches the above error (heading)</p>
  
  <p>Elaborated: when a row cell has value <em>Spread Duration--IR Swap</em>, need the corresponding column cell <em>FundSpreadDurationContribution</em> value.</p>
  
  <pre><code> double testvalue = Convert.ToDouble(raptorDS.Tables[RaptorTable.DurationContribBySector].AsEnumerable().Where(r =&gt;
                                           r.Field&lt;string&gt;(RaptorColumns.FundCode) == fundDescriptionColumn &amp;&amp;
                                           r.Field&lt;string&gt;(RaptorColumns.Component) == Component.B8_DURATION_CONTRIBUTION_BY_SECTOR &amp;&amp;
                                           r.Field&lt;string&gt;(RaptorColumns.Sector) == "Spread Duration--IR Swap").Select(s =&gt; s.Field&lt;string&gt;(RaptorColumns.FundSpreadDurationContribution)))
  </code></pre>
  
  <p>I am learner of LINQ.</p>