Thank you for your email.
It is good to know that you have printed OK for non covered insurance before.

In my case, I previewed the prescriptions which should be printed. Instead of the prescriptions expected, it showed some formula about Insurance calculation. It also said cannot use the calculation formula.

What it may mean is the AC program processes the request of printing the prescriptions but in the preparation of the output, Visual Basic programs (I guess AZ used VB but it maybe another software language) cannot process further so it displays that error message.
There is no output to print because the program cannot create the output due to the error.
Since you can print other non covered insurance prescriptions, perhaps in your case the formula can show the result is 0 dollars of coverage but it did not reject.

It is all speculations though.

For Greg, if you can re-print it then likely it was the Printer problem on the previous time.
If you cannot print it, do the same process and Preview it.
If the preview shows an error in calculation
then please post that to this board.