ROW_NUMBER , LEFT OUTER JOIN in LINQ

I have a List<int> dateList
20130531
20130601
20130603

and a DataTable dt with three columns
(Code string,
BusDate int,
Price double
)
ABC  20130531  5
ABC  20130602  4
ABC  20130603  7
LMN  20130601  3
LMN  20130602  2

I need to get for all the given dates in the List, the corresponding codes and prices.
If the date does not exist in the datatable, get the previous days price. Order by Code and date

The final result set should look like this based on the above example

ABC  20130531  5
ABC  20130601  5
ABC  20130603  7
LMN  20130531  NULL
LMN  20130601  3
LMN  20130603  2

This does not work
 var query = from c in dateList.AsEnumerable()
                        join p in dt.AsEnumerable() on c equals p["BusDate"] into ps
                        from p in ps.DefaultIfEmpty()
                        select new { BusDate = c, Code = p["Code"],  Price = p["Price"] };