Prescription Quantities defaulting to zero

Question:  Why are the prescription quantities defaulting to zero?

The order a prescription is written is important. In most cases the quantity will get overwritten with zero if the user enters the quantity first - and then - tries to modify the instructions. For instance:

1)  Prescribe aspirin
2)  Enter quantity 30
3)  Enter instruction: take one tablet prn
4)  Save Rx prior to review

The correct way to write the above Rx is:

1)  Prescribe aspirin
2)  Enter instruction: take one tablet prn
3)  Enter quantity: 30
4)  Review Rx
5)  Save

Of course the quantity will reset to zero if you go back and edit the instructions.