Cells with Similar Time Formatting Displaying Differently

[BrianExcel]

Why would a time calculation show up differently if they are formatted the same way?

I have 12 worksheets, each one a month of the year. In the upper left there are several time values. Some hard-coded and some calculated from data within the sheet.

On some sheets, I perform the calculation and the time value is negative, but shows up correctly (displayed in red text since it's negative), but then on others, the same calculation gives me a ########## value instead of the value itself. I don't understand why some cells would do this and some not.

Thoughts?

 

[VoG]

You need to be using the 1904 date system in order to display negative times.

 

[BrianExcel]

Thanks VOG. Can you point me in the direction of how to use the 1904 date system? Never looked into that one...

 

[VoG]

This may help http://support.microsoft.com/kb/180162