title: Not Having CopyToDatatable() method
body: <p>i have a linq to dataTable query like this:</p>
  
  <pre><code>`var ShowResult = from r in Result.AsEnumerable()
                               where Convert.ToInt32(r.Field&lt;double&gt;("ASLVAM") / r.Field&lt;double&gt;("GEST")) &gt; 60
                               orderby Convert.ToInt32(r.Field&lt;double&gt;("ASLVAM") / r.Field&lt;double&gt;("GEST")) descending 
                               select new
                               {
                                   pascode = r.Field&lt;string&gt;("PAS_CODE"),
                                   melli = r.Field&lt;string&gt;("CODEMELI"),
                                   name = r.Field&lt;string&gt;("NAM"),
                                   family = r.Field&lt;string&gt;("FAMILY"),
                                   bycode = r.Field&lt;string&gt;("BAYGANI"),
                                   jancode = r.Field&lt;string&gt;("CODEJANBAZ"),
                                   darsad = r.Field&lt;int&gt;("DARSAD"),
                                   ostan = r.Field&lt;string&gt;("OSTAN_N"),
                                   vacode = r.Field&lt;string&gt;("VA_CODE"),
                                   moin = r.Field&lt;string&gt;("VA_MOIN"),
                                   onvan = r.Field&lt;string&gt;("TAFZILI"),
                                   aslvam = r.Field&lt;double&gt;("ASLVAM"),
                                   gest = r.Field&lt;double&gt;("GEST"),
                                   //tededGestKol = Convert.ToInt32(r.Field&lt;double&gt;("ASLVAM") / r.Field&lt;double&gt;("GEST")),
                                   mandeVam = r.Field&lt;double&gt;("MANDE_VAM"),
                                   dPardakht = r.Field&lt;string&gt;("DATE_P")
                               };`&lt;code&gt;
  </code></pre>
  
  <p>
  and i added reference System.Data.DataSetExtentions to use CopyToDataTable() method for showing my query result in a dataGrid view but this method didn,t add to my Inellisence,
  I also use the <a href="http://msdn.microsoft.com/en-us/library/bb669096.aspx" rel="nofollow">MSDN Sample</a> to use this method but this time i got this error :
  "Specified Cast is not valid"
  Please help me , what can i do to overcom this problem?</p>