Preventing print when cells are blank
 

Hi
I have tried using the Excel icon and view code and
entered a piece of code to prevent users from printing out
if all cells are not completed. The problem is the cells
on the current sheet are linked to a previous sheet.
If the user clicks on an option button to say yes then I
have linked a cell on my print sheet =$a$1 (from previous
sheet) and I need to validate the cell so that if the user
does not choose yes or no and leaves it blank then an
error will appear preventing printing? Is this possible.
I hope I have made this clear??

Thanks