I have a situation where when I run this stored proc on the live database I get a timeout error. if I copy the two tables into a different dead database where there are no transactions happening, then I get a result instantly the table Jn has over 2 million records.

SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;

has not helped. Even WITH NOLOCK has not helped. any ideas pls ? stored proc is below

create PROCEDURE [dbo].[mysp]
@sRefDateFrom AS CHAR(8) , @sRefDateTo AS CHAR(8) -- Dates are expected in 'YYYYMMDD'
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
SELECT A.FormatCode, A.AcctName , SUM(J.Debit) AS Debit, SUM (J.Credit) AS Credit
FROM JN J
JOIN AC A
ON A.AcctCode = J.Account
WHERE J.RefDate >= @sRefDateFrom
AND J.RefDate <= @sRefDateTo
GROUP BY A.FormatCode , A.AcctName
ORDER BY A.FormatCode
END

I have a weird situation where (randomly) a previous Cell value is read by the Excel VBA code. eg: Cell 1A had a value = Y. It was updated to N. However a subsequent VBA code read the cell value as Y It has been hard to troubleshoot as this was a random occurrence. I was lucky to catch one today, and upon stepping through the code (using F8) discovered that the correct current value was read during debug!. Re-run the macro without debug mode and the correct value was read. Its very confusing and I cannot think of anything but an Excel bug. Have you encountered this issue at all and if so what solution/s have you applied. Thanks in advance.