Pete,

It appears I've plagiarized your post.  I wonder how I missed it.  If we
posted at similar times it could happen -- the Microsoft news server farm
has quite a bit of latency sometimes.  But if you're in the UK, then your
posting time should be later than mine, not earlier, to be concurrent.  Or I
wonder if you're on the West coast USA (I'm on the East coast).

Maybe I just didn't see it.  Sheesh, it's bad enough that posters put the
same question in multiple newsgroups, getting responders to work on
questions already answered.  Or sometimes even in the same group, separated
only by hours.

Oh, well.  You were there first.  Where's the damned coffee?

<snip>

Thank you both for the swift responses.

Earl, my problem wasn't the day rollover...it was getting an addition of any
sort.  Answer always NIL.

I believe I've fixed it now - the problem was something to do with how I
arrived at the hours in each cell.
Simple subtraction of two times (in this case 'Work Start' and 'Work
Finish') giving a 'Time' format answer (which didn't want to be added to
other cells)

Converting the time differences to straight text (=a2-a1) instead of time
format yeilds a correct solution.
Strangely, converting them to time format AFTER gaining the solution
reformats the cells *without* changing the correct solution.

I don't understand it...but it works so I'm happy.

My thanks to Pete for giving me a pointer to this workaround...if that's
what it is!

Cheers...