well, because your way $t is:

        [
          [ 1, 2, 4, 4 ],
          [ 5, 2, 0, 8 ],
          [ 9, 10, 11, 12 ],
        ]
[download]

when it should be:

        [
          [ 1, 5, 9 ],
          [ 2, 2, 10 ],
          [ 4 ],
          [ 4, 8, 12 ],
        ]
[download]

kinda different...