I have tried that formula, but it appears to show "oops!" in valid times, and
not in invalid ie the 8/1 doesn't show oops?

Please advise.

Date Start End
01-Jan 09.15 10.00
02-Jan 16.00 17.00 oops!
03-Jan 09.00 15.15
03-Jan 14.00 16.00 oops!
05-Jan 12.00 13.00 oops!
06-Jan 09.00 11.00 oops!
06-Jan 17.00 18.00
08-Jan 11.00 11.30
08-Jan 11.00 11.30



"daddylonglegs" wrote:


Assuming you have dates in column A from A2 down and the start times are
from B2, end times from C2

you could use this formula in D2 and copy down column

=IF(SUMPRODUCT(--(A$1:A$10+B$1:B$10<A1+B1),--(A$1:A$10+C$1:C$10A1+B1)),"oops!","")


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