Total Wage = Total Normal  + Total Overtime + Total Prevailing Wage 

Each of the above columns  are themselves a formula column with a datatype of Currency.

Despite the fact that one or more of these columns has data, Total Wage sometimes has no values. I can't figure out why.

I have tried

Total Wage = (Total Normal)  + (Total Overtime) + (Total Prevailing Wage )

I have also tried:

Total Wage = (Normal Hours * Normal Hourly Rate)  + (Overtime Hours * (1.5 * Normal Hourly Rate) + (Prevailing Wage Hours * Prevailing Wage Hourly Rate )

I also tried changing the data types of all fields to decimal.

Still no luck.

What could I possibly  be doing wrong?

Any help would be greatly appreciated.

-Kevin