title: how to get child elements for specific node XML with linq
body: <p>i need to get all activities for claim id = "0000526_INS012_5367676737" the below xml </p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;Header&gt;
      &lt;SenderID&gt;INS012&lt;/SenderID&gt;
      &lt;ReceiverID&gt;F-0000526&lt;/ReceiverID&gt;
      &lt;TransactionDate&gt;04/11/2014 01:07&lt;/TransactionDate&gt;
      &lt;RecordCount&gt;1&lt;/RecordCount&gt;
      &lt;DispositionFlag&gt;PRODUCTION&lt;/DispositionFlag&gt;
    &lt;/Header&gt;
    &lt;Claim&gt;
      &lt;ID&gt;DHA-F-0000526_INS012_20141007135247&lt;/ID&gt;
      &lt;IDPayer&gt;16175815&lt;/IDPayer&gt;
      &lt;ProviderID&gt;F-0000526&lt;/ProviderID&gt;
      &lt;Encounter&gt;
        &lt;FacilityID&gt;DHA-F-0000526&lt;/FacilityID&gt;
      &lt;/Encounter&gt;
      &lt;Activity&gt;
        &lt;ID&gt;779972&lt;/ID&gt;
        &lt;Start&gt;07/10/2014 13:53&lt;/Start&gt;
        &lt;Type&gt;5&lt;/Type&gt;
      &lt;/Activity&gt;
      &lt;Activity&gt;
        &lt;ID&gt;779973&lt;/ID&gt;
        &lt;Start&gt;07/10/2014 13:53&lt;/Start&gt;
        &lt;Type&gt;5&lt;/Type&gt;
      &lt;/Activity&gt;
      &lt;/Claim&gt;
    &lt;Claim&gt;
      &lt;ID&gt;0000526_INS012_5367676737&lt;/ID&gt;
      &lt;IDPayer&gt;16175815&lt;/IDPayer&gt;
      &lt;ProviderID&gt;F-0000526&lt;/ProviderID&gt;
      &lt;Encounter&gt;
        &lt;FacilityID&gt;DHA-F-0000526&lt;/FacilityID&gt;
      &lt;/Encounter&gt;
      &lt;Activity&gt;
        &lt;ID&gt;6767&lt;/ID&gt;
        &lt;Start&gt;07/10/2014 13:53&lt;/Start&gt;
        &lt;Type&gt;5&lt;/Type&gt;
      &lt;/Activity&gt;
      &lt;Activity&gt;
        &lt;ID&gt;67467&lt;/ID&gt;
        &lt;Start&gt;07/10/2014 13:53&lt;/Start&gt;
        &lt;Type&gt;5&lt;/Type&gt;
      &lt;/Activity&gt;
      &lt;/Claim&gt;
  &lt;/Remittance.Advice&gt;
  </code></pre>
  
  <p>i tried to do below code , but its not working </p>
  
  <pre><code>  var oooo = Doc.Descendants("Claim").Where(claim =&gt; claim.Element("ID").ToString() == ClaimList.CLAIM_ID)
                                                              .SelectMany(claim =&gt; claim.Elements("Activity"));
  </code></pre>