Right. Many thanks. I applied .First() to r1, but that did not work.

In fact it all boils down to :

DataRow r1 =customers.AsEnumerable().First(r => (r.Field<string>("ID") == ID));

>Instead of .Where, try .First or .FirstOrDefault. You'll need to test for condition where no records are returned.
>
>>Succeeded in getting this passed the editor. Note that customers is a DataTable.
>>

>>  IEnumerable<DataRow[]> r1 = (IEnumerable<DataRow[]>) customers.AsEnumerable().Where(r => (r["ID"] == ID));
>>

>>
>>now how do I get the first row cast as a DataRow?