Can someone tell me if it's possible to calculate time as a negative figure. I'm trying to do a calculation where if you work less than contracutual hours it shows up as -01:00 using the custom time format [h]mm:ss.

To be clear, I have a figure of 0:00:00 (zero hours) and a figure of 1:00:00 (1 hour) but when I do the =sum subtraction formula it comes back with the result of #######. All I need it to show is 0 hours minus 1 hour = -1 hour.

Any help much appreciated.

JCR