Unable to cast object of type

var q4 = from pf in db.ProjectsFiles
                            join p in db.Projects
                            on pf.ProjectID equals p.ProjectID
                            where (pf.ProjectID == Convert.ToInt32(CBDocDownPr.SelectedValue))
                            select new { pf.FileID, p.ProjectTitle, pf.FileTitle, pf.LoadTime, pf.PFile };

                dgvDocDownload.DataSource = q4;  

error : Unable to cast object of type '<>f__AnonymousType11`2[System.Int32,System.String]' to type 'System.IConvertible'.