How to get past the Insert Address Block in a Mail Merge for Labels?

I am using LO 5 with Win 10 64bit. I have an existing LO Base database that I am trying to use to create mailing labels in Writer. I am using an existing document with all the appropriate database fields selected/formated which I successfully used for the labels in the past. In the Insert Address Block dialog of the Mail Merge Wizard, I cannot select a registered database (and table) from the drop down menu and move on. (The correct base and table are in the ones shown in the drop down menu.) The OK button is grayed out. The database and query work fine in Base.
If I try to start a completely new Labels document, I can see/select the database successfully in the dialog box, but it will not see any of the tables/queries associated with the database in the next drop down menu/box for selection; therefore I cannot access and select the desired fields.
The labels routine has successfully worked in the past, but has now stopped.
Any help will be appreciated.

I solved my dilemma by unregisterng the reference database and then reregistering it.