title: cannot implicitly convert type when groupby
body: <p>I get this error when I try to group by <code>CellID</code>:</p>
  
  <blockquote>
    <p>Cannot implicitly convert type 'System.Collections.Generic.List
    System.Linq.IGrouping int,p2pControllerLogAnalyser.Models.GSMData' to
    'System.Collections.Generic.List
    p2pControllerLogAnalyser.Models.GSMData'</p>
  </blockquote>
  
  <pre><code>public List&lt;GSMData&gt; GetCellID()
  {
      return Gsmdata.GroupBy(x =&gt; x.CellID).ToList();
  }
  </code></pre>
  
  <p>What am I doing wrong and how can I fix it?</p>