Time difference exceeding 24 hours

I am trying to find time difference in hours, mins & seconds betwen 2 timestamps. If the difference between them is less than 24 hours, i get correct value. If it exceeds more than 24 hours, I get wrong answer.

Col 1 Col 2 Col 3 = Col 2- Col 1
8/1/12 16:00 8/2/12 14:10 22:09:59 - correct
8/2/12 16:00 8/3/12 6:50 14:50:06 - correct
8/3/12 16:00 8/4/12 7:37 15:36:59 - correct
8/5/12 14:00 8/6/12 2:57 12:57:18 - correct
8/6/12 16:00 8/7/12 16:11 0:10:58 - WRONG


Is there any way of calculating the time difference between two timestamps when it exceeds more than 24 hours.

Any help is greatly appricated.

Thanks.