Grid lines in Numbers

Has my Numbers 09 software (Version 2.3) become corrupted because I cannot switch on grid lines? Under Cell Borders in the Table Inspector there are options for left, right, bottom, top borders and one with a cross in that switches on borders between cells, but I cannot select all of them, e.g. if I select top border and then the bottom border, my first selection disappears! If I select the borders between cells (which is the nearest I can get to all grid lines on) when I print, the lines are missing!!

I can switch on alternating row colours which helps differentiate the rows but I need all grid lines showing. Can anyone help please?😟