Error report when finalising 2018 STP from Hosted 2018 R2

Have successfully processed one STP entry for our employee, using Hosted 2018 R2. Now I'm trying to finalise the second STP.  Feel as though I have correctly completed the file but when I got to the MyGov to upload the file (using the button "Update a previously completed ATO submission or Finalise Year"), it gives an error to the effect that "Total Gross and Total PAYG exists where not allowed".  Have no idea how to correct that.