Hi Peter,
Probably the difficulty is with getting an answer here is not indicating
exactly what you have for a formula and what is displayed in each cell,
and what you have in your macro.
You will get a #VALUE! on your worksheet has leading spaces in
the date for instance. It is not a number and would not by default
be right aligned. If the data came from HTML they might be
non-breakijg-space characters
Try making a copy of the worksheet and run the TRIMALL macro
on your date columns.
http://www.mvps.org/dmcritchie/excel/join.htm#trimall
if that does not work then try examining your data with the
functions like e ISNUMBER or ISTEXT additional things to
check are in the comments above the TRIMALL macro on that page.