MS SQL Server stored proc parameter problem

Fellow Delphians (and especially those also dabbling in MS SQL Server
6.5):

I am having a big problem with a query called by a stored proc - it is not
returning a legitimate value.
When I run the query in ISQL/W, it gives me the correct answer, but when I
call the stored proc that contains the query, it returns 0. Maybe I am
doing something wrong...?

Here is the query that works in ISQL/W:

SELECT
  SUM(Oil)
FROM
  Prodhold
WHERE
  Field = 'Coalinga'

Here is the stored proc that always returns 0 through its default
singleton result set COLUMN1:

CREATE PROC sp_mpoilf
  @Field varchar(50)
AS
SELECT
  SUM(Oil)
FROM
  prodhold
WHERE
  field = @Field

Here is the code I use to obtain the value:

with stpOilF do  
begin
  try
    Prepare;
    ExecProc;
  finally
    Unprepare;
  end;
end;

The @Field parameter _does_ contain the correct ('Coalinga') value when
the stored proc is executed.

Here is the code I use to retrieve the value:

tblMPPrintOilnCond.Value := stpOilFCOLUMN1.Value;

But the table always contains 0, as the stored procs result is 0. Does
anybody know why?

Clay Shannon,
IH...@aol.com