Please provide more information. fpvectorial supports many formats, and it is not clear which one you are using. Ideally you should post a compilable sample project which shows the issue (put .pas, .lfm, .lpr and .lpi files into a common .zip which you can upload here under "Attchments and other options"; don't add binaries and other compiler-generated files).
procedure DefaultBorder(var ABorder: TvTableBorder); begin ABorder.Width := 0.1; ABorder.LineType := tbtSingle; end; procedure DefaultCell(ACell: TvTableCell); begin DefaultBorder(ACell.Borders.Left); DefaultBorder(ACell.Borders.Right); DefaultBorder(ACell.Borders.Top); DefaultBorder(ACell.Borders.Bottom); end; ... for iCol := 0 to 4 do begin Cell := Row.AddCell; DefaultCell(Cell); // <---- NEW