cannot convert Iqueryable to EnumerableRowcollection-why?

EnumerableRowCollection<DataRow> erc=(from excel in _dc.Tablename where excel.column1.Equals(this.Name) select excel);


Error:Error 1 Cannot implicitly convert type 'System.Linq.IQueryable<DataAccessLayer.Linq.Validation>' to
'System.Data.EnumerableRowCollection<System.Data.DataRow>'. An explicit conversion exists (are you missing a cast?)