How can I put a sequential number on a mail merge label?

What I did:

1- on Writer I connected to Biblio table.

2- inserted two mail merge fields (ie.: Author & Title).

3- Inserted Record Number Field.

4- File > Print.

5- Answered Yes to “Your document contains address database fields. Do you want to print a form letter?”

6- Selected All records (or some of them).

7- Sent to Printer (or to File).

Correctly dispayed data of the recods selected, but the record number is the same on all labels.

Tried with other types of databases and/or using the Mail Merge Wizard with the same result.

Is there another way to number the labels sequentially?

Thanks to pierre-yves samyn , here is the answer:

Create a spreadsheet including the sequential numbers for your “Record Number” field (say 1 to 1000):

  • File New Spreadsheet
  • Type e.g. RecordNum in A1 (field title)
  • Click in the Name Box (left of formula bar),
    • type A2:A1001
    • Enter to select the range
  • Edit Fill Series:
    • Start Value 1,
    • End Value 1000,
    • Ok
  • Define this spreadsheet as source of mailing in your writer document: Edit > Exchange Database
  • Insert the RecordNum field in the header:
    • Drag & drop from the Data Sources view OR
    • Insert Fields More Fields, Database tab
  • Launch mailing and proceed as you did before