Workflow Calculation Logic Not Working

This post relates to a When New Record Saved workflow for a Revenue row on an opportunity.  the workflow has several action steps:

1. steps 1 and 2 pull in two number fields off the opportunity and populates this data on the revenue record.

2. step 3 updates the quantity as a simple multiplication of the above two number fields.

3.  step 4 and 5 pull in the MSRP and standard cost off the product chosen.

4. step 6 calculates the Total Cost.

there is no step to calculate the Revenue as the system does that automatically.

5. step 7 calculates a new currency field called Gross Profit which equals Revenue - Total Cost.