QS Rules ERROR after every Z REPORT?

Could anyone please help with a problem where having at our store?

If we run a z report at the end of the day, after there are sale on it, we always get this error:

run-time error '5'

Error #3709

Method '~' of object '' failed

..... if needed I can provide the rest of the error message.

If I just run a blank z report with no sale, this doesn't happen.

Thanks much!

NIck