Switch matrix.... not working

Can someone have a look at a circuit i have built....

i have a usb input board for analog and digital inputs, Leo bodnar's BU0836 board,

i want to use the 32 switch inputs possible by using the switch matrix style input,

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is the page with the board, and about a quarter way down is the diagram for the matrix, a pretty standard one, 6 columns, 6 rows, 36 diodes and the switches,

i have made a pcb from

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he has shown the pcb layout too,
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my pcb looks exactly as shown, i put in the 36 diodes in the right way, electrically it all works, switches are recognized by the windows joystick tester,

however i am getting input ghosting, which the diodes are supposed to stop,

i.e. i close switch 1, close say switch 30, if i then close switch 7, all is fine, but if i close switch 8, 7 and 8 are on, same for switch 9, 7 and 9 are on, when i get to the next column/row, it does the same, from switch 13, if switch 16 is on, switch 13 is too,

When i get to a certain point, i get 5 switch inputs on from 3 selected,

any ideas what I've done wrong? the row and column connections are on 6 way headers, I've tried swapping the header plugs over, so columns is in rows etc, still ghosting but reversed inputs, i.e. 36 is 1, reversing the plugs and no inputs detected, so the diodes are working, but something is not right, i have no solder bridges or anything, tested all the tracks with the multimeter, but I've done something wrong, unless the circuit diagram is wrong.

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