Your dates aren't what you think they are.

They could be completely different:
05/01/04 could be May 1, 2004 or January 5, 2004 or January 4, 2005.

Or they could be plain old text (that look like dates).

I'd select that range and give it a nice unambiguous date format, like:
mmmm dd, yyyy

And see what your data shows.

The values that are text won't change--you'll still see 03/06/05.

ps.
If this is a single cell:  3/01/05 - 03/06/05
then it's not a date--it's a string and will sort in plain old alphanumeric
order.

If you want to sort in date order, you'd be better off by putting the start and
end dates in different columns--and use real dates.

03/01/05 is an ambiguous format.  Format the cells as something unambiguous,
like dd mmm yyyy, and then you'll see what dates you are really dealing
with.
--
David Biddulph