Countdown to event timing.....

Hi, Im trying to build a workbook in Excel 2007 that is able to calculate
the amount of time REMAINING until the start of a scheduled event and return
the number of hours, minutes and seconds remaining until the scheduled start
time, however if the event does not start on time I want to be able to see
how many hours, minutes and seconds the event is running late.

I have built a worksheet that returns the following information (hh:mm:ss)

Current Time 13:25:34
Expected Start Time 14:00:00
Variance 00:34:26

However if an event starts later than expected I want the return to look
like this:

Current Time 14:07:44
Expected Start Time 14:00:00
Variance (00:07:44)

Instead what I actually get is either Variance = 23:59:59 or Variance = VALUE!

Any help that you can give would be great, please include any details
regarding the cell formatting as I suspect that this is where Im going wrong.

Thanks.