title: How to solve IEnumerable<DataRow> Value cannot be null. Parameter name: value
body: <p>Can you explain what difference error at parameter value and source?
  I try to query at DataTable so need convert to IEnumerable.</p>
  
  <pre><code>IEnumerable&lt;DataRow&gt; tablecust = datasetcust.Tables[0].AsEnumerable();
  </code></pre>
  
  <p>And then query</p>
  
  <pre><code>DataRow cust = tablecust
      .Where(x=&gt; x.Field&lt;string&gt;("Name") == "Customer1" 
              &amp;&amp; x.Field&lt;string&gt;("Address") == "Karet" )
      .FirstOrDefault();
  </code></pre>
  
  <p>I got error : </p>
  
  <pre><code>Value cannot be null. Parameter name : value
  </code></pre>
  
  <p>Can anyone explain this? </p>
  
  <p>Thanks</p>