I am creating a timesheet for my office, but have hit a wall with calculating overtime.

Currently, I have a final hours cell showing in cell A1 with total hours as 52:00:00 as 52 hours worked. When I try to use a formula in cell a2 to calculate overtime like =sum(A1-40) to get 12 hours of overtime, it just returns the ###### symbols.

Anyone??

Thank you in advance.