Sheet freeze for excel using JXL jar

Question

I'm creating a excel file in java using JXL jar, and I'm using th following code to freeze the row.

   Label lable = new Label(0, 6, "Sl No", tableSubHeaderCellFormat);
   sheet.addCell(lable);
   sheet.mergeCells(0, 6, 0, 7);
   sheet.getSettings().setVerticalFreeze(11);

The freeze works fine, but since the freeze is applied (here to the 11th row) to the entire row, a line continues to appear along the row which is being freezed, and I don't want that line to appear. Any suggestions?