The specified LINQ expression contains references to queries that are associated with different contexts error in c#
<p>I want to execute this query :</p>

<pre><code>public List&lt;ViewSheet&gt; ShowSheet(List&lt;Sheet&gt; lst)
{
   var res = (from sheet in _sheetRepository.Get()
       join line in _lineRepository.Get() on sheet.LineId equals line.Id
       join basemat in _baseMaterialRepository.Get() on sheet.BaseMaterialId equals basemat.Id
       join lineend in _lineEndRepository.Get() on sheet.LineEndId equals lineend.Id
       join Paint in _paintCodeRepository.Get() on sheet.PaintCodeId equals Paint.Id 
       select new ViewSheet()
       {
           BaseMaterialId = basemat.Name,
           Catagory = sheet.Catagory,

           LineEndId = lineend.Name,
           LineId = line.LineNumber,
           MtPercent = sheet.MtPercent,
           PAndId = sheet.PAndId,
           PaintCodeId = Paint.Name,
           ParentId = sheet.ParentId,

       }).ToList();
   return res;
}
</code></pre>

<p>as you can see i create a join between 4 tables and the <code>get</code> function has this structure :</p>

<pre><code>public interface ISheetRepository
{
    IQueryable&lt;Sheet&gt; Get();
    bool Save();       
}
</code></pre>

<p>But i get this error :</p>

<blockquote>
  <p>The specified LINQ expression contains references to queries that are
  associated with different contexts.</p>
</blockquote>