What's happening? It works for me. I guess the most obvious issues
might be:

-Make sure you have installed morefunc.
-Typos.
-The "12" argument of XLM.GET.CELL checks the bottom border. A border
could be a top border and appear like the bottom of the cell above,
but would not be counted. There are arguments to check all 4 sides of
cells for borders, the formula can be modified to suit.
-You do have to force a manual calculation for this. Simply changing
cells in the specified array will not re-calc this function, so hit
F9. This is true of Excel's built-in CELL function, too, IIRC.