The 20-pin goes in against one end (if you have it in right, it will seat to the bottom) - not in the middle - the orange wires end of the 20-pin plug should be tight against one end (leaving 4-contacts open on the other end) and the latches of both plug and socket must be on the same side - latches may not line up properly, use a couple dabs of hot glue to hold it in place. Or you can get a 20-24wire adapter (~ $4. on newegg).
.bh.
:moon: