How to get MailMerge to put data into Labels

I have created a spreadsheet with my address data for my labels. I created a registered database based on this spreadsheet. I did File->New->Labels using Avery A$ type of L7165 and setup a label using the database’s table fields. I then did View->Sources and saw the address data above the sheet of labels. However, when I did Tools->MailMerge, on the 4th screen it greyed out next preventing me to go to the 5th and 6th screens and therefore the labels page was not populated with the address data. I’m using LO 5.4.3.2 under Ubuntu 16.04. This worked OK a year ago under a previous version of LO also under Ubuntu 16.04. Is there a workaround?