Error calculating earnings: The piece rate for this Step cannot be calculated.

There is probably not a Prevailing Wage or Standard Pieces set for the current date.  You can correct this using the Job Setup subject.

1. From the Navigator, select Job/Activity Setup.
2. Click on the Job Step affected.
   1. Verify there is a Prevailing Wage with a current date.
   2. Verify there are pieces set with current dates in the Time Study area.